Dual Filtered Graphs for Kac-Moody algebras

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Date

2024-05-08

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Publisher

Virginia Tech

Abstract

We construct a strong filtered graph Γs(Λ) dependent on the dominant weight Λ, and a weak filtered graph Γw(\Kcen) dependent on the canonical central element \Kcen for an arbitrary Kac-Moody algebra g. In our construction, both graphs (Γs(Λ),Γw(\Kcen)) have the vertex set as the Weyl group of g, with the grading given by the length function. The edges of the graph Γs(\La) are labeled versions of the λ-chain model of K-Chevalley rules for Kac-Moody flag manifolds as developed by Lenart and Shimozono, originally defined by Lenart and Postnikov. Meanwhile, the labels on Γw(\Kcen) come from the dual multiplication map of K-cohomology of affine Grassmannian GrG. We conjecture that the strong filtered graph and weak filtered graph are dual, which means we get an identity when we apply the up and down operators on the vertices. We proved this identity except one case that where we call the chain is j-present. Our identity is similar to the Möbius construction of the dual filtered graph, as previously studied by Patrias and Pylyavskyy, and in fact, in the limit n of the An−1(1), our construction recovers their identity. We also expect to recover their combinatorics of Möbius deformation of the shifted Young's lattice in type Cn(1) as n approaches infinity.

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Keywords

Dual filtered graphs, $lambda$-chain, K-theory, Affine Schubert calculus.

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