Shi arrangements restricted to Weyl cones
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arXiv
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| Format: | Preprint |
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2022
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| _version_ | 1866911203006087168 |
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| author | Dorpalen-Barry, Galen Stump, Christian |
| author_facet | Dorpalen-Barry, Galen Stump, Christian |
| contents | We consider the restrictions of Shi arrangements to Weyl cones, their relations to antichains in the root poset, and their intersection posets. For any Weyl cone, we provide bijections between regions, flats intersecting the cone, and antichains of a naturally-defined subposet of the root poset. This gives a refinement of the parking function numbers via the Poincaré polynomials of the intersection posets of all Weyl cones. Finally, we interpret these Poincaré polynomials as the Hilbert series of three isomorphic graded rings. One of these rings arises from the Varchenko-Gel'fand ring, another is the coordinate ring of the vertices of the order polytope of a subposet of the root poset, and the third is purely combinatorial. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2204_05829 |
| institution | arXiv |
| publishDate | 2022 |
| record_format | arxiv |
| spellingShingle | Shi arrangements restricted to Weyl cones Dorpalen-Barry, Galen Stump, Christian Combinatorics Primary 20F55, Secondary 52C35 We consider the restrictions of Shi arrangements to Weyl cones, their relations to antichains in the root poset, and their intersection posets. For any Weyl cone, we provide bijections between regions, flats intersecting the cone, and antichains of a naturally-defined subposet of the root poset. This gives a refinement of the parking function numbers via the Poincaré polynomials of the intersection posets of all Weyl cones. Finally, we interpret these Poincaré polynomials as the Hilbert series of three isomorphic graded rings. One of these rings arises from the Varchenko-Gel'fand ring, another is the coordinate ring of the vertices of the order polytope of a subposet of the root poset, and the third is purely combinatorial. |
| title | Shi arrangements restricted to Weyl cones |
| topic | Combinatorics Primary 20F55, Secondary 52C35 |
| url | https://arxiv.org/abs/2204.05829 |