University of Kentucky Discrete CATS Seminar
U N I V E R S I T Y   O F   K E N T U C K Y


2017 -- 2018

Fall 2017

Unless otherwise noted, seminar meets at 2:00 pm Mondays in 745 POT.

Sept 18 Richard Ehrenborg
University of Kentucky
Simion's type B associahedron is a pulling triangulation of the Legendre polytope
We show that the Simion type B associahedron is combinatorially equivalent to a pulling triangulation of the type A root polytope known as the Legendre polytope. Furthermore, we show that every pulling triangulation of the boundary of the Legendre polytope yields a flag complex. Our triangulation refines a decomposition of the boundary of the Legendre polytope given by Cho.

This is joint work with Gábor Hetyei and Margaret Readdy.

Sept 25 Zhexiu Tu
Centre College
Topological Representations of Matroids and the cd-index
There are several different topological representations of non-orientable matroids. In this talk, inspired by Swartz's work, I will show an explicit fully partitioned homotopy sphere d-arrangement S that is a CW-complex whose intersection lattice is the geometric lattice of the corresponding matroid for matroids of rank < 5. Moreover S has a d-sphere in it that is a regular CW-complex. We will also look at enumerative properties, including how the flag f-vector formula of Billera, Ehrenborg and Readdy for oriented matroids applies to arbitrary matroids.
Oct 2 Alex Happ
University of Kentucky
Oct 9 Olsen McCabe
University of Kentucky
Oct 16 Brian Davis
University of Kentucky
Regular triangulations and Gröbner bases
Oct 23 No meeting

Oct 30 Rafael González D'león Universidad Sergio Arboleda
and York University
The Whitney dual of a graded poset
Nov 6 Megan Bernstein
Georgia Tech
Nov 13 Radmila Sazdanovic
NC State University
Nov 20 Open date

Nov 27 Joseph Cummings
University of Kentucky
Dec 4 Open date

Spring 2018

Seminar Archive

Margaret Readdy is the organizer of the Discrete CATS Seminar. If you wish to be added to the seminar list or give a talk, please e-mail her at margaret.readdy (at)

We would like to thank Benjamin Braun (NSA 2013--2015), Richard Ehrenborg (Simons Foundation Collaboration Grant 2016--2021), Margaret Readdy (Simons Foundation Collaboration Grant 2016--2021) and Martha Yip (Simons Foundation Collaboration Grant 2016--2021) who generously continue to support our speakers with their grants. The Discrete CATS seminar is also partially supported by the University of Kentucky Department of Mathematics.

Last updated September 15, 2017.