2019/03/25 by Fink, Alex, Mészáros, Karola, Dizier, Avery St.
#Combinatorics (math.CO) #FOS: Mathematics
paper · doi:10.48550/arxiv.1903.10332
We prove that if σ∈ Sm is a pattern of w ∈ Sn, then we can express the Schubert polynomial \mathfrakSw as a monomial times \mathfrakSσ (in reindexed variables) plus a polynomial with nonnegative coefficients. This implies that the set of permutations whose Schubert polynomials have all their coefficients equal to either 0 or 1 is closed under pattern containment. Using Magyar's orthodontia, we characterize this class by a list of twelve avoided patterns. We also give other equivalent conditions on \mathfrakSw being zero-one. In this case, the Schubert polynomial \mathfrakSw is equal to the integer point transform of a generalized permutahedron.