Quiver Grassmannians of Extended Dynkin type 𝐷 Part 1: Schubert Systems and Decompositions Into Affine Spaces

2019 ◽  
Vol 261 (1258) ◽  
pp. 0-0
Author(s):  
Oliver Lorscheid ◽  
Thorsten Weist
Keyword(s):  
Affine Spaces ◽  
Quiver Grassmannians ◽  
Dynkin Type

scholarly journals Quiver Grassmannians of Type $\widetilde {D}_{n}$, Part 2: Schubert Decompositions and F-polynomials

2021 ◽  
Author(s):  
Oliver Lorscheid ◽  
Thorsten Weist
Keyword(s):  
Cluster Algebras ◽  
Indecomposable Representation ◽  
Euler Characteristics ◽  
Affine Spaces ◽  
Quiver Grassmannians ◽  
Small Defect ◽  
Quiver Grassmannian ◽  
Vertex Set ◽  
Explicit Formulae ◽  
Fixed Tree

AbstractExtending the main result of Lorscheid and Weist (2015), in the first part of this paper we show that every quiver Grassmannian of an indecomposable representation of a quiver of type $\tilde D_{n}$ D ~ n has a decomposition into affine spaces. In the case of real root representations of small defect, the non-empty cells are in one-to-one correspondence to certain, so called non-contradictory, subsets of the vertex set of a fixed tree-shaped coefficient quiver. In the second part, we use this characterization to determine the generating functions of the Euler characteristics of the quiver Grassmannians (resp. F-polynomials). Along these lines, we obtain explicit formulae for all cluster variables of cluster algebras coming from quivers of type $\tilde D_{n}$ D ~ n .

scholarly journals Cell decompositions and algebraicity of cohomology for quiver Grassmannians

2021 ◽  
Vol 379 ◽  
pp. 107544
Author(s):  
Giovanni Cerulli Irelli ◽  
Francesco Esposito ◽  
Hans Franzen ◽  
Markus Reineke
Keyword(s):  
Quiver Grassmannians ◽  
Cell Decompositions

scholarly journals The close relation between border and Pommaret marked bases

2021 ◽  
Author(s):  
Cristina Bertone ◽  
Francesca Cioffi
Keyword(s):  
Finite Order ◽  
Polynomial Ring ◽  
Group Actions ◽  
Close Relation ◽  
Open Covering ◽  
Order Ideal ◽  
Lower Dimension ◽  
Hilbert Schemes ◽  
Affine Spaces ◽  
The Ideal

AbstractGiven a finite order ideal $${\mathcal {O}}$$ O in the polynomial ring $$K[x_1,\ldots , x_n]$$ K [ x 1 , … , x n ] over a field K, let $$\partial {\mathcal {O}}$$ ∂ O be the border of $${\mathcal {O}}$$ O and $${\mathcal {P}}_{\mathcal {O}}$$ P O the Pommaret basis of the ideal generated by the terms outside $${\mathcal {O}}$$ O . In the framework of reduction structures introduced by Ceria, Mora, Roggero in 2019, we investigate relations among $$\partial {\mathcal {O}}$$ ∂ O -marked sets (resp. bases) and $${\mathcal {P}}_{\mathcal {O}}$$ P O -marked sets (resp. bases). We prove that a $$\partial {\mathcal {O}}$$ ∂ O -marked set B is a marked basis if and only if the $${\mathcal {P}}_{\mathcal {O}}$$ P O -marked set P contained in B is a marked basis and generates the same ideal as B. Using a functorial description of these marked bases, as a byproduct we obtain that the affine schemes respectively parameterizing $$\partial {\mathcal {O}}$$ ∂ O -marked bases and $${\mathcal {P}}_{\mathcal {O}}$$ P O -marked bases are isomorphic. We are able to describe this isomorphism as a projection that can be explicitly constructed without the use of Gröbner elimination techniques. In particular, we obtain a straightforward embedding of border schemes in affine spaces of lower dimension. Furthermore, we observe that Pommaret marked schemes give an open covering of Hilbert schemes parameterizing 0-dimensional schemes without any group actions. Several examples are given throughout the paper.

scholarly journals Quotients of cluster categories

2010 ◽  
Vol 140 (1) ◽  
pp. 65-81 ◽  
Author(s):  
Peter Jørgensen
Keyword(s):  
The Other ◽  
Dynkin Type ◽  
Cluster Categories

Higher cluster categories were recently introduced as a generalization of cluster categories. This paper shows that in Dynkin types A and D, half of all higher cluster categories can be obtained as quotients of cluster categories. The other half are quotients of 2-cluster categories, the ‘lowest’ type of higher cluster categories. Hence, in Dynkin types A and D, all higher cluster phenomena are implicit in cluster categories and 2-cluster categories. In contrast, the same is not true in Dynkin type E.

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