Συνδυαστική Θεωρία (ΘΜ29)

Η ακόλουθη διάλεξη σχετίζεται με την ύλη που καλύψαμε στο μάθημα αυτό το εξάμηνο:

Ημερομηνία: Τετάρτη 18/1/2023
Ώρα: 11:00
Αίθουσα: Α31

Speaker: Dr. Paolo Sentinelli, Politecnico di Milano

Title: Linear extensions and shelling orders

Abstract: We will explore the Bruhat order on the set of facets of a pure
simplicial complex (viewed as Grassmannian permutations) and its
barycentric subdivision (viewed in a non-standard ambient, a quotient  of
a symmetric group). We are led to the results that linear extensions  of
order ideals of the first ambient poset are shelling orders and that  that
linear extensions of order ideals of the second ambient poset are  flag
shelling orders, a notion which will be introduced in the talk. Similar
results hold for matroids and some other Coxeter matroids. We end by
defining promotion and evacuation operators on shelling orders.