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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

We show the existence of quasi-cluster $\mathcal{A}$-structures and cluster Poisson structures on moduli stacks of sheaves with singular support in the alternating strand diagram of grid plabic graphs by studying the microlocal parallel…

Symplectic Geometry · Mathematics 2024-01-01 Roger Casals , Daping Weng

LP algebras, introduced by Lam and Pylyavskyy, are a generalization of cluster algebras. These algebras are known to have the Laurent phenomenon, but positivity remains conjectural. Graph LP algebras are finite LP algebras encoded by a…

Combinatorics · Mathematics 2022-11-28 Esther Banaian , Sunita Chepuri , Elizabeth Kelley , Sylvester W. Zhang

In the cluster algebra literature, the notion of a graded cluster algebra has been implicit since the origin of the subject. In this work, we wish to bring this aspect of cluster algebra theory to the foreground and promote its study. We…

Rings and Algebras · Mathematics 2015-06-22 Jan E. Grabowski

One hundred years ago, Hilbert gave a list of important open problems in mathematics. His 15th problem asked for the development of a rigorous calculus explaining Schubert's enumerative results for intersecting varieties defined by rank…

Combinatorics · Mathematics 2025-06-27 Sara C. Billey , Yibo Gao , Brendan Pawlowski

We give a closed-form formula for the Hilbert function of the tangent cone at the identity of a Schubert variety X in the Grassmannian in both group theoretic and combinatorial terms. We also give a formula for the multiplicity of X at the…

Algebraic Geometry · Mathematics 2007-05-23 V. Kreiman , V. Lakshmibai

This paper continues the study of cluster algebras initiated in math.RT/0104151. Its main result is the complete classification of the cluster algebras of finite type, i.e., those with finitely many clusters. This classification turns out…

Rings and Algebras · Mathematics 2015-06-26 Sergey Fomin , Andrei Zelevinsky

In 2016, Leclerc constructed conjectural cluster structures on open Richardson varieties using representations of preprojective algebras. A variant with more explicit seeds was obtained by M\'enard in his thesis. We show that M\'enard's…

Representation Theory · Mathematics 2022-07-22 Peigen Cao , Bernhard Keller

We introduce a Poisson variety compatible with a cluster algebra structure and a compatible toric action on this variety. We study Poisson and topological properties of the union of generic orbits of this toric action. In particular, we…

Quantum Algebra · Mathematics 2007-05-23 M. Gekhtman , M. Shapiro , A. Vainshtein

We describe all Poisson brackets compatible with the natural cluster algebra structure in the open Schubert cell of the Grassmannian $G_k(n)$ and show that any such bracket endows $G_k(n)$ with a structure of a Poisson homogeneous space…

Quantum Algebra · Mathematics 2016-05-25 Michael Gekhtman , Michael Shapiro , Alexander Stolin , Alek Vainshtein

A plabic graph is a planar bicolored graph embedded in a disk, which satisfies some combinatorial conditions. Postnikov's boundary measurement map takes the space of positive edge weights of a plabic graph $G$ to a positroid cell in some…

Combinatorics · Mathematics 2017-03-21 Rachel Karpman , Yi Su

Cluster categories were introduced in 2006 by Buan-Marsh-Reineke-Reiten-Todorov in order to categorify acyclic cluster algebras without coefficients. Their construction was generalized by Amiot (2009) and Plamondon (2011) to arbitrary…

Representation Theory · Mathematics 2023-04-11 Yilin Wu

In the construction of a cluster algebra on the homogeneous coordinate ring of a partial flag variety by Gei{\ss}, Leclerc and Schr{\"{o}}er, they defined a special map denoted by ``tilde". This map lifts each element $f$ of the coordinate…

Rings and Algebras · Mathematics 2024-03-19 Fayadh Kadhem

Graph LP algebras are a generalization of cluster algebras introduced by Lam and Pylyavskyy. We provide a combinatorial proof of positivity for certain cluster variables in these algebras. This proof uses a hypergraph generalization of…

Combinatorics · Mathematics 2023-12-20 Esther Banaian , Sunita Chepuri , Elizabeth Kelley , Sylvester W. Zhang

Let X be the flag variety of the symplectic group. We propose a theory of combinatorially explicit Schubert polynomials which represent the Schubert classes in the Borel presentation of the cohomology ring of X. We use these polynomials to…

Algebraic Geometry · Mathematics 2014-02-26 Harry Tamvakis

Cluster algebras are commutative rings with a set of distinguished generators having a remarkable combinatorial structure. They were introduced by Fomin and Zelevinsky in 2000 in the context of Lie theory, but have since appeared in many…

Rings and Algebras · Mathematics 2013-03-19 Lauren K. Williams

In a classical-type flag variety, we consider a Schubert variety associated to a vexillary (signed) permutation, and establish a combinatorial formula for the Hilbert-Samuel multiplicity of a point on such a Schubert variety. The formula is…

Algebraic Geometry · Mathematics 2021-12-15 David Anderson , Takeshi Ikeda , Minyoung Jeon , Ryotaro Kawago

We study the deformation theory of the Stanley-Reisner rings associated to cluster complexes for skew-symmetrizable cluster algebras of geometric and finite cluster type. In particular, we show that in the skew-symmetric case, these cluster…

Algebraic Geometry · Mathematics 2025-03-03 Nathan Ilten , Alfredo Nájera Chávez , Hipolito Treffinger

These are notes for a series of lectures presented at the ASIDE conference 2016. The definition of a cluster algebra is motivated through several examples, namely Markov triples, the Grassmannians $Gr_2(\mathbb{C})$, and the appearance of…

Combinatorics · Mathematics 2018-03-28 Max Glick , Dylan Rupel

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