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| Content Provider | Springer Nature Link |
|---|---|
| Author | Athanasiadis, Christos A. Tzanaki, Eleni |
| Copyright Year | 2006 |
| Abstract | Let Φ be an irreducible crystallographic root system with Weyl group W and coroot lattice $$\check{Q}$$ , spanning a Euclidean space V. Let m be a positive integer and $${\mathcal A}^{m}_{\Phi}$$ be the arrangement of hyperplanes in V of the form $$(\alpha, x) = k$$ for $$\alpha \in \Phi$$ and $$k = 0, 1,\dots,m$$ . It is known that the number $$N^+ (\Phi, m)$$ of bounded dominant regions of $${\mathcal A}^{m}_{\Phi}$$ is equal to the number of facets of the positive part $$\Delta^m_+ (\Phi)$$ of the generalized cluster complex associated to the pair $$(\Phi, m)$$ by S. Fomin and N. Reading.We define a statistic on the set of bounded dominant regions of $${\mathcal A}^{m}_{\Phi}$$ and conjecture that the corresponding refinement of $$N^+ (\Phi, m)$$ coincides with the $h$-vector of $$\Delta^m_+ (\Phi)$$ . We compute these refined numbers for the classical root systems as well as for all root systems when m = 1 and verify the conjecture when Φ has type A, B or C and when m = 1. We give several combinatorial interpretations to these numbers in terms of chains of order ideals in the root poset of Φ, orbits of the action of W on the quotient $$\check{Q} / \, (mh-1) \, \check{Q}$$ and coroot lattice points inside a certain simplex, analogous to the ones given by the first author in the case of the set of all dominant regions of $${\mathcal A}^{m}_{\Phi}$$ . We also provide a dual interpretation in terms of order filters in the root poset of Φ in the special case m = 1. |
| Starting Page | 355 |
| Ending Page | 375 |
| Page Count | 21 |
| File Format | |
| ISSN | 09259899 |
| Journal | Journal of Algebraic Combinatorics |
| Volume Number | 23 |
| Issue Number | 4 |
| e-ISSN | 15729192 |
| Language | English |
| Publisher | Kluwer Academic Publishers |
| Publisher Date | 2006-01-01 |
| Publisher Place | Boston |
| Access Restriction | One Nation One Subscription (ONOS) |
| Subject Keyword | Catalan arrangement Bounded region Generalized cluster complex Positive part h-vector Computer Science Group Theory and Generalizations Order, Lattices, Ordered Algebraic Structures Combinatorics Convex and Discrete Geometry |
| Content Type | Text |
| Resource Type | Article |
| Subject | Discrete Mathematics and Combinatorics Algebra and Number Theory |
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