Susanna Fishel ; Eleni Tzanaki ; Monica Vazirani
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Counting Shi regions with a fixed separating wall
dmtcs:2916 -
Discrete Mathematics & Theoretical Computer Science,
January 1, 2011,
DMTCS Proceedings vol. AO, 23rd International Conference on Formal Power Series and Algebraic Combinatorics (FPSAC 2011)
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https://doi.org/10.46298/dmtcs.2916
Counting Shi regions with a fixed separating wallArticle
1 School of Mathematical and Statistical Sciences (Arizona, Tempe)
2 Department of Applied Mathematics [Heraklion]
3 Department of Mathematics [Univ California Davis]
Athanasiadis introduced separating walls for a region in the extended Shi arrangement and used them to generalize the Narayana numbers. In this paper, we fix a hyperplane in the extended Shi arrangement for type A and calculate the number of dominant regions which have the fixed hyperplane as a separating wall; that is, regions where the hyperplane supports a facet of the region and separates the region from the origin.