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We enumerate factorizations of a Coxeter element in a well generated complex reflection group into arbitrary factors, keeping track of the fixed space dimension of each factor. In the infinite families of generalized permutations, our…

Combinatorics · Mathematics 2024-02-07 Joel Brewster Lewis , Alejandro H. Morales

We introduce $n(n-1)/2$ natural involutions ("toggles") on the set $S$ of noncrossing partitions $\pi$ of size $n$, along with certain composite operations obtained by composing these involutions. We show that for many operations $T$ of…

The Kreweras complementation map is an anti-isomorphism on the lattice of noncrossing partitions. We consider an analogous operation for plane trees motivated by the molecular biology problem of RNA folding. In this context, we explicitly…

Combinatorics · Mathematics 2023-03-23 Christine Heitsch

Let W be a finite crystallographic reflection group. The generalized Catalan number of W coincides both with the number of clusters in the cluster algebra associated to W, and with the number of noncrossing partitions for W. Natural…

Representation Theory · Mathematics 2011-06-15 Aslak Bakke Buan , Idun Reiten , Hugh Thomas

For a finite real reflection group $W$ we use non-crossing partitions of type $W$ to construct finite cell complexes with the homotopy type of the Milnor fiber of the associated $W$-discriminant $\Delta_W$ and that of the Milnor fiber of…

Group Theory · Mathematics 2018-12-19 Thomas Brady , Michael Falk , Colum Watt

We define noncrossing partitions of a marked surface without punctures (interior marked points). We show that the natural partial order on noncrossing partitions is a graded lattice and describe its rank function topologically. Lower…

Combinatorics · Mathematics 2026-05-22 Nathan Reading

Our basic objects are partitions of finite sets of points into disjoint subsets. We investigate sets of partitions which are closed under taking tensor products, composition and involution, and which contain certain base partitions. These…

Combinatorics · Mathematics 2015-09-04 Pierre Tarrago , Moritz Weber

In this paper we prove that the set of non-crossing forests together with a cyclic group acting on it by rotation and a natural q-analogue of the formula for their number exhibits the cyclic sieving phenomenon, as conjectured by Alan Guo.

Combinatorics · Mathematics 2011-06-07 Stefan Kluge

Each finite configuration of points in the plane determines a corresponding lattice of noncrossing partitions. When these points form the vertex set of a convex polygon, the associated lattice is the classical noncrossing partition lattice…

Combinatorics · Mathematics 2026-04-17 Michael Dougherty , Gina Root

For any positive integers $a$ and $b$, we enumerate all colored partitions made by noncrossing diagonals of a convex polygon into polygons whose number of sides is congruent to $b$ modulo $a$. For the number of such partitions made by a…

Combinatorics · Mathematics 2017-01-23 Daniel Birmajer , Juan B. Gil , Michael D. Weiner

We develop the relationship between minimal transitive star factorizations and noncrossing partitions. This gives a new combinatorial proof of a result by Irving and Rattan, and a specialization of a result of Kreweras. It also arises in a…

Combinatorics · Mathematics 2021-04-09 Bridget Eileen Tenner

Let $n$ be a non-negative integer and $A=\{a_1,\ldots,a_k\}$ be a multi-set with $k$ not necessarily distinct members, where $a_1\leqslant\ldots\leqslant a_k$. We denote by $\Delta(n,A)$ the number of ways to partition $n$ as the form…

Combinatorics · Mathematics 2018-05-22 Toufik Mansour , Madjid Mirzavaziri , Daniel Yaqubi

The present thesis studies structural properties of non-crossing partitions associated to finite Coxeter groups from both algebraic and geometric perspectives. On the one hand, non-crossing partitions are lattices, and on the other hand, we…

Combinatorics · Mathematics 2019-03-18 Julia Heller

Let $X$ be a nonempty real variety that is invariant under the action of a reflection group $G$. We conjecture that if $X$ is defined in terms of the first $k$ basic invariants of $G$ (ordered by degree), then $X$ meets a $k$-dimensional…

Algebraic Geometry · Mathematics 2017-06-08 Tobias Friedl , Cordian Riener , Raman Sanyal

In this paper, we study the lattice properties of posets of torsion pairs in the module category of a family of representation-finite gentle algebras called tiling algebras, introduced by Coelho Simoes and Parsons. We present a…

Representation Theory · Mathematics 2016-09-13 Alexander Garver , Thomas McConville

We present a direct bijection between descending plane partitions with no special parts and permutation matrices. This bijection has the desirable property that the number of parts of the descending plane partition corresponds to the…

Combinatorics · Mathematics 2012-07-26 Jessica Striker

We prove that the noncrossing partition lattices associated with the complex reflection groups $G(d,d,n)$ for $d,n\geq 2$ admit symmetric decompositions into Boolean subposets. As a result, these lattices have the strong Sperner property…

Combinatorics · Mathematics 2017-08-08 Henri Mühle

For a set of nonnegative integers $S$ let $R_{S}(n)$ denote the number of unordered representations of the integer $n$ as the sum of two different terms from $S$. In this paper we focus on partitions of the natural numbers into two sets…

Number Theory · Mathematics 2016-08-22 Sándor Z. Kiss , Csaba Sándor

We show how Coxeter's work implies a bijection between complex reflection groups of rank two and real reflection groups in $O(3)$. We also consider this magic square of reflections and rotations in the framework of Clifford algebras: we…

Group Theory · Mathematics 2024-01-23 Ragnar-Olaf Buchweitz , Eleonore Faber , Colin Ingalls

We answer an open problem of arXiv:1204.1760 and arXiv:1205.4293, extending their work to irreducible well--generated complex reflection groups $W$. We define a combinatorial $W$-noncrossing parking space and an algebraic $W$-parking space…

Combinatorics · Mathematics 2025-02-05 Jason Stack