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We consider the Poisson sigma model associated to a Poisson manifold. The perturbative quantization of this model yields the Kontsevich star product formula. We study here the classical model in the Hamiltonian formalism. The phase space is…

Symplectic Geometry · Mathematics 2020-05-29 Alberto S. Cattaneo , Giovanni Felder

A dimer model is a quiver with faces embedded into a disk. A consistent dimer model gives rise to a strand diagram, and hence to a positroid. The Gorenstein-projective module category over the completed boundary algebra of a dimer model was…

Representation Theory · Mathematics 2024-04-04 Jonah Berggren , Khrystyna Serhiyenko

The square of a skew-symmetric matrix is a symmetric matrix whose eigenvalues have even multiplicities. When the matrices have rank two, they represent the Grassmannian of lines, and the squaring operation takes Pl\"ucker coordinates to…

Algebraic Geometry · Mathematics 2026-02-02 Hannah Friedman , Andrea Rosana , Bernd Sturmfels

Richardson varieties play an important role in intersection theory and in the geometric interpretation of the Littlewood-Richardson Rule for flag varieties. We discuss three natural generalizations of Richardson varieties which we call…

Algebraic Geometry · Mathematics 2010-08-18 Sara Billey , Izzet Coskun

Let $G$ be a simple, simply connected, simply laced algebraic group. We construct a monoidal category of representations of the quantum affine algebra $U_q(\widehat{\mathfrak{g}})$ whose Grothendieck ring contains a cluster algebra with…

Representation Theory · Mathematics 2026-05-26 Yingjin Bi

In this paper we construct arbitrarily large families of smooth projective varieties and closed Riemannian manifolds that share many algebraic and analytic invariants. For instance, every non-arithmetic, closed hyperbolic $3$--manifold…

Geometric Topology · Mathematics 2018-04-02 D. Arapura , J. Katz , D. B. McReynolds , P. Solapurkar

We study Riemannian manifolds carrying a metric connection with parallel, skew-symmetric and closed torsion, which we call in short PSCT manifolds. We prove that PSCT manifolds always locally split into a product of well-understood factors,…

Differential Geometry · Mathematics 2026-05-14 Andrei Moroianu , Paul Schwahn

In this paper, a description of the set-theoretical defining equations of symplectic (type C) Grassmannian/flag/Schubert varieties in corresponding (type A) algebraic varieties is given as linear polynomials in Pl$\ddot{u}$cker coordinates,…

Algebraic Geometry · Mathematics 2023-04-21 Jiajun Xu , Guanglian Zhang

We give a new Littlewood-Richardson rule for the Schubert structure coefficients of isotropic Grassmannians, equivalently for the multiplication of $P$-Schur functions. Serrano (2010) previously gave a formula in terms of classes in his…

Combinatorics · Mathematics 2025-06-23 Santiago Estupiñán-Salamanca , Oliver Pechenik

We construct ribbon surfaces of Euler characteristic one for several infinite families of alternating 3-braid closures. We also use a twisted Alexander polynomial obstruction to conclude the classification of smoothly slice knots which are…

Geometric Topology · Mathematics 2023-06-22 Vitalijs Brejevs

We investigate the role that non-crossing partitions play in the study of positroids, a class of matroids introduced by Postnikov. We prove that every positroid can be constructed uniquely by choosing a non-crossing partition on the ground…

Combinatorics · Mathematics 2013-09-17 Federico Ardila , Felipe Rincón , Lauren Williams

Categorical skew lattices are a variety of skew lattices on which the natural partial order is especially well behaved. While most skew lattices of interest are categorical, not all are. They are characterized by a countable family of…

Rings and Algebras · Mathematics 2012-10-18 Michael Kinyon , Jonathan Leech

Let $K$ be a finite group and let $G$ be a finite group acting on $K$ by automorphisms. In this paper we study two different but intimately related subjects: on the one side we classify all possible multiplicative and associative structures…

Quantum Algebra · Mathematics 2021-03-08 César Galindo , Ismael Gutiérrez , Bernardo Uribe

We construct all skew braces of size $pq$ (where $p>q$ are primes) by using Byott's classification of Hopf--Galois extensions of the same degree. For $p\not\equiv 1 \pmod{q}$ there exists only one skew brace which is the trivial one. When…

Group Theory · Mathematics 2020-06-16 E. Acri , M. Bonatto

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

We study the category of G(O)-equivariant perverse coherent sheaves on the affine Grassmannian of G. This coherent Satake category is not semisimple and its convolution product is not symmetric, in contrast with the usual constructible…

Representation Theory · Mathematics 2018-04-30 Sabin Cautis , Harold Williams

We classify self-injective radical cube zero algebras with respect to whether they satisfy certain finite generation conditions sufficient to have a fruitful theory of support varieties defined via Hochschild cohomology in the vein of…

Representation Theory · Mathematics 2024-11-26 Mads Hustad Sandøy

The affine Grassmannian of $SL_n$ admits an embedding into the Sato Grassmannian, which further admits a Pl\"ucker embedding into the projectivization of Fermion Fock space. Kreiman, Lakshmibai, Magyar, and Weyman describe the linear part…

Algebraic Geometry · Mathematics 2018-06-18 Dinakar Muthiah , Alex Weekes , Oded Yacobi

We study the smooth projective symmetric variety of Picard number one that compactifies the exceptional complex Lie group G2, by describing it in terms of vector bundles on the spinor variety of Spin(14). We call it the double Cayley…

Algebraic Geometry · Mathematics 2020-04-02 Laurent Manivel

The aim of this paper is to find all algebraic threefolds admitting quasi-regular Poisson structure. There are three types of such varieties: abelian varieties, smooth flat conic bundles over abelian surfaces and quotients of the product of…

Algebraic Geometry · Mathematics 2007-05-23 Druel Stephane