Braid variety cluster structures, I: 3D plabic graphs

P Galashin, T Lam, M Sherman-Bennett… - arXiv preprint arXiv …, 2022 - arxiv.org
We introduce $3 $-dimensional generalizations of Postnikov's plabic graphs and use them
to establish cluster structures for type $ A $ braid varieties. Our results include known cluster …

The generalized cluster complex: refined enumeration of faces and related parking spaces

T Douvropoulos, M Josuat-Vergès - SIGMA. Symmetry, Integrability and …, 2023 - emis.de
The generalized cluster complex was introduced by Fomin and Reading, as a natural
extension of the Fomin-Zelevinsky cluster complex coming from finite type cluster algebras …

Pop, Crackle, Snap (and Pow): some facets of shards

C Defant, N Williams - arXiv preprint arXiv:2209.05392, 2022 - arxiv.org
Reading cut the hyperplanes in a real central arrangement $\mathcal H $ into pieces
called\emph {shards}, which reflect order-theoretic properties of the arrangement. We show …

Charmed roots and the Kroweras complement

B Dequêne, G Frieden, A Iraci… - Journal of the …, 2024 - Wiley Online Library
Although both noncrossing partitions and nonnesting partitions are uniformly enumerated for
Weyl groups, the exact relationship between these two sets of combinatorial objects remains …

[PDF][PDF] Recursions and Proofs in Cataland

T Douvropoulos, M Josuat-Vergès - mh, 2023 - emis.de
We give the first type-independent proof of the Kreweras-style formulas for the enumeration
of noncrossing partitions in a real reflection group W, with respect to parabolic type. This …

Rational Catalan Numbers for Complex Reflection Groups

W Miller - arXiv preprint arXiv:2310.12354, 2023 - arxiv.org
Assuming standard conjectures, we show that the canonical symmetrizing trace evaluated at
powers of a Coxeter element produces rational Catalan numbers for irreducible spetsial …

Combinatorics and Braid Varieties

N Williams - Open Problems in Algebraic Combinatorics, 2024 - books.google.com
I summarize a framework for finding and proving interesting combinatorial formulas using
braid varieties. The combinatorics comes from the Deodhar decomposition of these braid …

An elaborate new proof of Cayley's formula

E Banaian, ATN Hoang, E Kelley, W Miller… - arXiv preprint arXiv …, 2024 - arxiv.org
We construct a bijection between certain Deodhar components of a braid variety constructed
from an affine Kac-Moody group of type $ A_ {n-1} $ and vertex-labeled trees on $ n …

Lattice Points and Rational -Catalan Numbers

D Armstrong - arXiv preprint arXiv:2403.06318, 2024 - arxiv.org
For each pair of coprime integers $ a $ and $ b $ one defines the" rational $ q $-Catalan
number" $\mathrm {Cat} _q (a, b)=\bigl [\hskip-1.5 pt\begin {smallmatrix}{a-1+ b}\\{a-1}\end …

[PDF][PDF] Oberwolfach problem session: Enumerative combinatorics 2022

N Williams - 2022 - utdallas.edu
Fix a multiset ̂S of small steps, and consider all walks W (̂S) from (2, 0) to (− 1, 0) using
the collection of steps in ̂S that avoid the negative x and y axes, except at the final point of …