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Documents  Marsh, Robert J. | enregistrements trouvés : 6

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Research talks;Combinatorics;Algebraic and Complex Geometry;Topology

I will discuss a connection between the topology of isolated singularities of plane curves and the mutation equivalence of the quivers associated with their morsifications. Joint work with Pavlo Pylyavskyy, Eugenii Shustin, and Dylan Thurston.

13F60 ; 20F36 ; 57M25 ; 58K65

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Research talks;Algebraic and Complex Geometry;Mathematical Physics

The geometric Satake equivalence identifies the Satake category of a reductive group $G$ - that is, the category of equivariant perverse sheaves on the affine Grassmannian $G_{rG}$ - with the representation category of its Langlands dual group $G^∨$. While the Satake category is topological in nature, it has a poorly understood algebro-geometric cousin: the category of perverse coherent sheaves on $G_{rG}$. This category is not semi-simple and its monoidal product is not symmetric. We show however that it is rigid and admits renormalized r-matrices similar to those appearing in the theory of quantum loop or KLR algebras. Applying the framework developed by Kang-Kashiwara-Kim-Oh in their proof of the dual canonical basis conjecture, we use these results to show that the coherent Satake category of $GL_n$ is a monoidal cluster categorification in the sense of Hernandez-Leclerc. This clarifies the physical meaning of the coherent Satake category: simple perverse coherent sheaves correspond to Wilson-’t Hooft operators in $\mathcal{N} = 2$ gauge theory, just as simple perverse sheaves correspond to ’t Hooft operators in $\mathcal{N} = 4$ gauge theory following the work of Kapustin-Witten. Our results also explain the appearance of identical quivers in the work of Kedem-Di Francesco on $Q$-systems and in the context of BPS quivers. More generally, our construction of renormalized r-matrices works in any chiral $E_1$-category, providing a new way of understanding the ubiquity of cluster algebras in $\mathcal{N} = 2$ field theory: the existence of renormalized r-matrices, hence of iterated cluster mutation, is a formal feature of such theories after passing to their holomorphic-topological twists. This is joint work with Sabin Cautis (arXiv:1801.08111). The geometric Satake equivalence identifies the Satake category of a reductive group $G$ - that is, the category of equivariant perverse sheaves on the affine Grassmannian $G_{rG}$ - with the representation category of its Langlands dual group $G^∨$. While the Satake category is topological in nature, it has a poorly understood algebro-geometric cousin: the category of perverse coherent sheaves on $G_{rG}$. This category is not semi-simple and ...

14D24 ; 14F05 ; 14M15 ; 18D10 ; 13F60 ; 17B37 ; 81T13

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Research talks;Algebra;Mathematical Physics

The theory of cluster algebras has proved useful in proving theorems about the characters of graded tensor products or Demazure modules, via the $Q$-system. Upon quantization, the algebra associated with this system is shown to be related to a quantum affine algebra. Graded characters are related to a polynomial representation of the quantum cluster variables. This immediately suggests a further deformation to the spherical DAHA, quantum toroidal algebras and elliptic Hall algebras. The theory of cluster algebras has proved useful in proving theorems about the characters of graded tensor products or Demazure modules, via the $Q$-system. Upon quantization, the algebra associated with this system is shown to be related to a quantum affine algebra. Graded characters are related to a polynomial representation of the quantum cluster variables. This immediately suggests a further deformation to the spherical DAHA, quantum ...

13F60 ; 17B37 ; 81R50 ; 17B10

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Research talks;Combinatorics;Algebraic and Complex Geometry

In joint work with Konstanze Rietsch (arXiv:1712.00447), we use the $\mathcal{X}$-cluster structure on the Grassmannian and the combinatorics of plabic graphs to associate a Newton-Okounkov body to each $\mathcal{X}$-cluster. This gives, for each $\mathcal{X}$-cluster, a toric degeneration of the Grassmannian. We also describe the Newton-Okounkov bodies quite explicitly: we show that their facets can be read off from $\mathcal{A}$-cluster expansions of the superpotential. And we give a combinatorial formula for the lattice points of the Newton-Okounkov bodies, which has a surprising interpretation in terms of quantum Schubert calculus. In joint work with Konstanze Rietsch (arXiv:1712.00447), we use the $\mathcal{X}$-cluster structure on the Grassmannian and the combinatorics of plabic graphs to associate a Newton-Okounkov body to each $\mathcal{X}$-cluster. This gives, for each $\mathcal{X}$-cluster, a toric degeneration of the Grassmannian. We also describe the Newton-Okounkov bodies quite explicitly: we show that their facets can be read off from $\mathcal{A}$-cluster ...

05E10 ; 14M15 ; 14M25 ; 14M27

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Research talks;Algebra;Combinatorics

The preprojective algebra $P$ of a quiver $Q$ has a family of ideals $I_w$ parametrized by elements $w$ in the Coxeter group $W$. For the factor algebra $P_w = P/I_w$, I will discuss tilting and cluster tilting theory for Cohen-Macaulay $P_w$-modules following works by Buan-I-Reiten-Scott, Amiot-Reiten-Todorov and Yuta Kimura.

13F60 ; 16G20 ; 18E30

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- 117 p.
ISBN 978-3-03719-130-9

Zürich lectures in advanced mathematics

Localisation : Ouvrage RdC (MARS)

associaèdre # algèbre à grappes # diagramme de Dynkin # type de mutation fini # Grassmannienne # phénomène de Laurent # groupe de réflexion # périodicité # polytope # mutation de carquois # système racinaire # suite de Somos # surface

13F60 ; 05E40 ; 14M15 ; 17B22 ; 17B63 ; 18E30 ; 20F55 ; 51F15 ; 52B05 ; 52B11 ; 57Q15

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