## KU Combinatorics Seminar Spring 2017

The Combinatorics Seminar meets on Friday in Snow 408 from 3-4pm.

Please contact Jeremy Martin if you are interested in speaking.

Friday 1/20
No seminar

Friday 1/27
Organizational meeting

Friday 2/3
Marge Bayer/Jeremy Martin
Background material for the paper Relative Stanley-Reisner theory and Upper Bound Theorems for Minkowski sums by Karim Adiprasito and Raman Sanyal [Publ. Math. IHES 124 (2016), 99-163]

Friday 2/10
Long Dao
Stanley's proof of the Upper Bound Conjecture for simplicial spheres

Friday 2/17
Bennet Goeckner
Balanced Cohen-Macaulay complexes

Friday 2/24
Joseph Doolittle
Cayley polytopes and Minkowski sums

Friday 3/3
No seminar

Friday 3/10
Cass Sherman (Oklahoma State)
Polynomials of Stretched Littlewood-Richardson Numbers

Abstract: Littlewood-Richardson (L-R) coefficients describe multiplicities of irreducible representations in a tensor product. They depend on combinatorial parameters called weights. These can be stretched by any positive integer. For a fixed set of weights, one considers the effect of stretching on L-R numbers, i.e. the function which associates to an integer $$N$$ the L-R coefficient with the weights stretched by $$N$$. This function is a polynomial with many nice properties. In this talk, we will discuss these properties and their relationship to the algebraic geometry of a certain polarized moduli space $$(M,L)$$, connected to the L-R numbers by a famous theorem of Borel-Weil.

Friday 3/17
TBA

Friday 3/24
No seminar (Spring Break)

Friday 3/31
Ken Duna
Title TBA

Friday 4/7
Jeremy Martin
Simplicial and Cellular Spanning Trees

Abstract: Counting spanning trees in graphs is a classical topic, dating back at least as far as Kirchhoff's discovery of the Matrix-Tree Theorem in the 1840s. Much of the theory of tree enumeration carries over to the higher-dimensional setting, where the graph is replaced with a simplicial or CW-complex - but with a twist. I will strive to make this talk should be accessible to all graduate students.

### April 7-9: Graduate Student Combinatorics Conference

Friday 4/14
Arturo Jaramillo
Cumulants and moments for products of free random variables

Friday 4/21
No seminar

Friday 4/28
Brandon Caudell
Oral Presentation for Departmental Honors

Friday 5/5
No seminar (Stop Day)

For seminars from previous semesters, please see the KU Combinatorics Group page.

Last updated Thu 5/15/17