Algebraic and Enumerative Combinatorics Seminar - Alejandro Morales Borrero

Thursday, November 16, 2023 2:00 pm - 2:00 pm EST (GMT -05:00)

Title: Linear relations and Lorentzian property of chromatic symmetric functions

Speaker: Alejandro Morales Borrero
Affiliation: Université du Québec à Montréal
Location: MC 6029

There will be a pre-seminar presenting relevant background at the beginning graduate level starting at 1:00 pm.

Abstract: The chromatic symmetric function (CSF) of Dyck paths of Stanley and its Shareshian Wachs q-analogue (q-CSF) have important connections to Hessenberg varieties, diagonal harmonics and LLT polynomials. In the, so called, abelian case they are related to placements of non-attacking rooks by results of Stanley-Stembridge (1993) and Guay-Paquet (2013).

In the first part of the talk, I will discuss a linear relation of the q-CSF for abelian paths in terms of the Garsia--Remmel q-rook and q-hit numbers originally due to Guay-Paquet and its relation to the e-positivity conjecture of Stanley--Stembridge and Shareshian--Wachs. This is joint work with Colmenarejo and Panova. In the second part of the talk, I will discuss the Newton polytope of CSFs of Dyck paths, whether it is saturated, and a conjectured Lorenztian property for these CSFs that is true for the abelian case. This is joint work with Matherne and Selover.