Richard P. Stanley Seminar in Combinatorics: Linear relations and Lorentzian property of chromatic symmetric functions


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May 10, 2023 4:15 pm - 5:15 pm
MIT, Room 2-139

Alejandro Morales - UMass Amherst

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.


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