8 papers
Self-dual intervals in the Bruhat order
Christian Gaetz, Yibo Gao
Björner-Ekedahl prove that general intervals in Bruhat order are "top-heavy", with at least as many elements in the -th corank as the -th rank. Well-known results of…
Separable elements and splittings of Weyl groups
Christian Gaetz, Yibo Gao
We continue the study of separable elements in finite Weyl groups. These elements generalize the well-studied class of separable permutations. We show that the multiplication map $…
Separable elements in Weyl groups
Christian Gaetz, Yibo Gao
We define the notion of a separable element in a finite Weyl group, generalizing the well-studied class of separable permutations. We prove that the upper and lower order ideals in…
Padded Schubert polynomials and weighted enumeration of Bruhat chains
Christian Gaetz, Yibo Gao
We prove a common generalization of the fact that the weighted number of maximal chains in the strong Bruhat order on the symmetric group is for both the code weig…
On the Sperner property for the absolute order on complex reflection groups
Christian Gaetz, Yibo Gao
Two partial orders on a reflection group, the codimension order and the prefix order, are together called the absolute order when they agree. We show that in this case the absolute…
A combinatorial duality between the weak and strong Bruhat orders
Christian Gaetz, Yibo Gao
In recent work, the authors used an order lowering operator , introduced by Stanley, to prove the strong Sperner property for the weak Bruhat order on the symmetric group.…