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Cluster algebras *with coefficients* are important since they appear in nature as coordinate algebras of varieties like Grassmannians, double Bruhat cells, unipotent cells, ... . The approach of Geiss-Leclerc-Schr\"oer often yields…

Representation Theory · Mathematics 2023-12-19 Chris Fraser , Bernhard Keller , Yilin Wu

Points in the intersection of Schubert varieties are counted by various combinatorial objects, for example standard tableaux. This paper consider the problem of producing a natural labelling of intersection points by these combinatorial…

Representation Theory · Mathematics 2019-12-24 Noah White

We construct the twist automorphism of open Richardson varieties inside the flag variety of a complex semisimple algebraic group. We show that the twist map preserves totally positive parts, and prove a Chamber Ansatz formula for it. Our…

Representation Theory · Mathematics 2022-10-11 Pavel Galashin , Thomas Lam

We introduce a superpotential for partial flag varieties of type $A$. This is a map $W: Y^\circ \to \mathbb{C}$, where $Y^\circ$ is the complement of an anticanonical divisor on a product of Grassmannians. The map $W$ is expressed in terms…

Algebraic Geometry · Mathematics 2020-11-17 Elana Kalashnikov

We describe a ring whose category of Cohen-Macaulay modules provides an additive categorification of the cluster algebra structure on the homogeneous coordinate ring of the Grassmannian of k-planes in n-space. More precisely, there is a…

Representation Theory · Mathematics 2017-05-17 Bernt Tore Jensen , Alastair King , Xiuping Su

We give positive combinatorial descriptions of Schubert structure constants $c_{u,v}^w$ for the full flag variety in type $A_{n-1}$ when $u$ and $v$ form what we refer to as a "$(p,q)$-pair" ($p+q=n$). The key observation is that a certain…

Combinatorics · Mathematics 2012-09-07 Benjamin J. Wyser

In this work we extend some previously known results on the automorphism group of Schubert varieties. We consider the Schubert conditions which define a Schubert variety. An automorphism of the Grassmannian fixes a Schubert variety…

Algebraic Geometry · Mathematics 2017-01-10 Fernando Piñero

Many interesting spaces --- including all positroid strata and wild character varieties --- are moduli of constructible sheaves on a surface with microsupport in a Legendrian link. We show that the existence of cluster structures on these…

Symplectic Geometry · Mathematics 2019-12-19 Vivek Shende , David Treumann , Harold Williams , Eric Zaslow

Generalizing the results by Fomin-Pylyavskyy and Carde, we construct a family of natural cluster structures in the coordinate ring of a mixed Grassmannian, the configuration space of tuples of several vectors and covectors in a…

Combinatorics · Mathematics 2025-06-26 Zenan Fu

We give positive descriptions for certain Schubert structure constants $c_{u,v}^w$ for the full flag variety in Lie types $C$ and $D$. This is accomplished by first observing that a number of the $K=GL(n,\C)$-orbit closures on these flag…

Combinatorics · Mathematics 2012-07-02 Benjamin J. Wyser

Skew shaped positroids (or skew shaped positroid varieties) are certain Richardson varieties in the flag variety that admit a realization as explicit subvarieties of the Grassmannian $\mathrm{Gr}(k,n)$. They are parametrized by a pair of…

Algebraic Geometry · Mathematics 2025-03-10 Eugene Gorsky , Soyeon Kim , Tonie Scroggin , José Simental

We provide a cluster-algebraic approach to the computation of the recently introduced generalised biadjoint scalar amplitudes related to Grassmannians ${\rm Gr}(k,n)$. A finite cluster algebra provides a natural triangulation for the…

High Energy Physics - Theory · Physics 2021-01-26 James Drummond , Jack Foster , Ömer Gürdoğan , Chrysostomos Kalousios

We study spherical Schubert varieties in the affine Grassmannian. These Schubert varieties have a natural conjectural modular description due to Finkelberg-Mirkovi\'c. This modular description is easily seen to be set-theoretically correct,…

Representation Theory · Mathematics 2016-04-04 Joel Kamnitzer , Dinakar Muthiah , Alex Weekes

Our motivation is to build a systematic method in order to investigate the structure of cluster algebras of geometric type. The method is given through the notion of mixing-type sub-seeds, the theory of seed homomorphisms and the view-point…

Rings and Algebras · Mathematics 2016-08-19 Min Huang , Fang Li , Yichao Yang

We study Hilbert-Samuel multiplicity for points of Schubert varieties in the complete flag variety, by Groebner degenerations of the Kazhdan-Lusztig ideal. In the covexillary case, we give a positive combinatorial rule for multiplicity by…

Algebraic Geometry · Mathematics 2011-11-08 Li Li , Alexander Yong

We develop a version of cluster algebra extending the ring of Laurent polynomials by adding Grassmann variables. These algebras can be described in terms of `extended quivers' which are oriented hypergraphs. We describe mutations of such…

Combinatorics · Mathematics 2019-02-28 Valentin Ovsienko , Michael Shapiro

The homogeneous coordinate ring of the Grassmannian $\rm{Gr}(k,n)$ has a well-known cluster structure. There is a categorification of this cluster structure via a category of modules for a ring $A_{k,n}$ due to Jensen-King-Su, building on…

Representation Theory · Mathematics 2026-02-16 Ian Le , Emine Yıldırım

We mainly introduce an abstract pattern to study cluster algebras. Cluster algebras, generalized cluster algebras and Laurent phenomenon algebras are unified in the language of generalized Laurent phenomenon algebras (briefly, GLP algebras)…

Representation Theory · Mathematics 2017-11-27 Peigen Cao , Fang Li

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

We define an action of the extended affine d-strand braid group on the open positroid stratum in the Grassmannian Gr(k,n), for d the greatest common divisor of k and n. The action is by quasi-automorphisms of the cluster structure on the…

Combinatorics · Mathematics 2018-08-17 Chris Fraser