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By work of a number of authors, beginning with Scott and culminating with Galashin and Lam, the coordinate rings of positroid varieties in the Grassmannian carry cluster algebra structures. In fact, they typically carry many such…

Combinatorics · Mathematics 2025-12-05 Matthew Pressland

In this article we explain how the coordinate ring of each (open) Schubert variety in the Grassmannian can be identified with a cluster algebra, whose combinatorial structure is encoded using (target labelings of) Postnikov's plabic graphs.…

Combinatorics · Mathematics 2019-08-07 K. Serhiyenko , M. Sherman-Bennett , L. Williams

The purpose of this note is to connect two maps related to certain graphs embedded in the disc. The first is Postnikov's boundary measurement map, which combines partition functions of matchings in the graph into a map from an algebraic…

Combinatorics · Mathematics 2017-11-22 Greg Muller , David E Speyer

Considered as commutative algebras, cluster algebras can be very unpleasant objects. However, the first author introduced a condition known as "local acyclicity" which implies that cluster algebras behave reasonably. One of the earliest and…

Combinatorics · Mathematics 2015-06-23 Greg Muller , David E. Speyer

Plabic graphs are intimately connected to the positroid stratification of the positive Grassmannian. The duals to these graphs are quivers, and it is possible to associate to them cluster algebras. For the top-cell graph of $Gr_{+}(k,n)$,…

High Energy Physics - Theory · Physics 2015-06-22 Miguel F. Paulos , Burkhard U. W. Schwab

We relate the mixed Hodge structure on the cohomology of open positroid varieties (in particular, their Betti numbers over $\mathbb{C}$ and point counts over $\mathbb{F}_q$) to Khovanov--Rozansky homology of associated links. We deduce that…

Combinatorics · Mathematics 2023-09-11 Pavel Galashin , Thomas Lam

We show that the dimer algebra of a connected Postnikov diagram in the disc is bimodule internally 3-Calabi-Yau in the sense of the author's earlier work. As a consequence, we obtain an additive categorification of the cluster algebra…

Representation Theory · Mathematics 2022-11-18 Matthew Pressland

We give an explicit combinatorial description of cluster structures in Schubert varieties of the Grassmannian in terms of (target labelings of) Postnikov's plabic graphs. This description is a natural generalization of the description given…

Combinatorics · Mathematics 2018-11-08 Khrystyna Serhiyenko , Melissa Sherman-Bennett , Lauren Williams

We show coordinate rings of open Richardson varieties are upper cluster algebras for any symmetrizable Kac--Moody type. We further show the coordinate rings of (generalized) open Richardson varieties on the twisted product of flag varieties…

Representation Theory · Mathematics 2025-08-11 Huanchen Bao , Jeff York Ye

We construct an explicit isomorphism between an open subset in the open positroid variety $\Pi_{k,n}^{\circ}$ in the Grassmannian $\mathrm{Gr}(k,n)$ and the product of two open positroid varieties $\Pi_{k,n-a+1}^{\circ}\times…

Algebraic Geometry · Mathematics 2024-05-27 Eugene Gorsky , Tonie Scroggin

We review some important results by Gross, Hacking, Keel, and Kontsevich on cluster algebra theory, namely, the column sign-coherence of $C$-matrices and the Laurent positivity, both of which were conjectured by Fomin and Zelevinsky. We…

Combinatorics · Mathematics 2023-02-23 Tomoki Nakanishi

We show the existence of cluster $\mathcal{A}$-structures and cluster Poisson structures on any braid variety, for any simple Lie group. The construction is achieved via weave calculus and a tropicalization of Lusztig's coordinates. Several…

Representation Theory · Mathematics 2024-11-07 Roger Casals , Eugene Gorsky , Mikhail Gorsky , Ian Le , Linhui Shen , José Simental

This paper demonstrates that the homogeneous coordinate ring of the Grassmannian $\Bbb{G}(k,n)$ is a {\it cluster algebra of geometric type} - as defined by S. Fomin and A. Zelevinsky. Grassmannians having {\it finite cluster type} are…

Combinatorics · Mathematics 2007-05-23 Joshua S. Scott

We show that the coordinate ring of a simply-connected simple algebraic group $G$ over the complex number field coincides with the Berenstein--Fomin--Zelevinsky cluster algebra and its upper cluster algebra, at least when $G$ is not of type…

Representation Theory · Mathematics 2026-04-02 Hironori Oya

We construct scattering diagrams for Chekhov-Shapiro's generalized cluster algebras where exchange polynomials are factorized into binomials, generalizing the cluster scattering diagrams of Gross, Hacking, Keel and Kontsevich. They turn out…

Algebraic Geometry · Mathematics 2024-10-23 Lang Mou

Cluster varieties come in pairs: for any $\mathcal{X}$ cluster variety there is an associated Fock-Goncharov dual $\mathcal{A}$ cluster variety. On the other hand, in the context of mirror symmetry, associated with any log Calabi-Yau…

Algebraic Geometry · Mathematics 2023-08-01 Hülya Argüz , Pierrick Bousseau

The Grassmannian is a disjoint union of open positroid varieties $P_v$, certain smooth irreducible subvarieties whose definition is motivated by total positivity. The coordinate ring of $P_v$ is a cluster algebra, and each reduced plabic…

Combinatorics · Mathematics 2022-01-07 Chris Fraser , Melissa Sherman-Bennett

Recently, Ramos and Whiting showed that any generalized cluster algebra of geometric type is isomorphic to a quotient of a subalgebra of a certain cluster algebra. Based on their idea and method, we show that the same property holds for any…

Representation Theory · Mathematics 2026-01-13 Ryota Akagi , Tomoki Nakanishi

We give a geometric interpretation of cluster varieties in terms of blowups of toric varieties. This enables us to provide, among other results, an elementary geometric proof of the Laurent phenomenon for cluster algebras (of geometric…

Algebraic Geometry · Mathematics 2014-04-16 Mark Gross , Paul Hacking , Sean Keel

Various coordinate rings of varieties appearing in the theory of Poisson Lie groups and Poisson homogeneous spaces belong to the large, axiomatically defined class of symmetric Poisson nilpotent algebras, e.g. coordinate rings of Schubert…

Commutative Algebra · Mathematics 2018-01-24 K. R. Goodearl , M. T. Yakimov
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