Skip to main content

Discrete CATS Seminar

745 POT
Speaker(s) / Presenter(s):
Galen Dorpalen-Barry, Ruhr-Universität Bochum (via Zoom)

Speaker:  Galen Dorpalen-Barry, Ruhr-Universität Bochum

Title:   The Poincaré-extended ab-index


Motivated by a conjecture of Maglione-Voll from group theory, we introduce and study the Poincaré-extended ab-index. This polynomial generalizes both the ab-index and the Poincaré polynomial.  For posets admitting R-labelings, we prove that the coefficients are nonnegative and give a combinatorial description of the coefficients. This proves Maglione-Voll's conjecture as well as a conjecture of the Kühne-Maglione. We also recover, generalize, and unify results from Billera-Ehrenborg-Readdy, Ehrenborg, and Saliola-Thomas.

This is joint work with Joshua Maglione and Christian Stump.

We will be meeting in 745 POT and the speaker will be live from Germany via Zoom.


Our website:

Type of Event (for grouping events):