On floors and ceilings of the \(k\)-Catalan arrangement
The electronic journal of combinatorics, Tome 21 (2014) no. 4
The set of dominant regions of the $k$-Catalan arrangement of a crystallographic root system $\Phi$ is a well-studied object enumerated by the Fuß-Catalan number $Cat^{(k)}(\Phi)$. It is natural to refine this enumeration by considering floors and ceilings of dominant regions. A conjecture of Armstrong states that counting dominant regions by their number of floors of a certain height gives the same distribution as counting dominant regions by their number of ceilings of the same height. We prove this conjecture using a bijection that provides even more refined enumerative information.
DOI :
10.37236/4121
Classification :
52C35, 05A15, 17B22
Mots-clés : Fuss-Catalan combinatorics, Catalan arrangement, floors, ceilings
Mots-clés : Fuss-Catalan combinatorics, Catalan arrangement, floors, ceilings
Affiliations des auteurs :
Marko Thiel  1
@article{10_37236_4121,
author = {Marko Thiel},
title = {On floors and ceilings of the {\(k\)-Catalan} arrangement},
journal = {The electronic journal of combinatorics},
year = {2014},
volume = {21},
number = {4},
doi = {10.37236/4121},
zbl = {1321.52027},
url = {http://geodesic.mathdoc.fr/articles/10.37236/4121/}
}
Marko Thiel. On floors and ceilings of the \(k\)-Catalan arrangement. The electronic journal of combinatorics, Tome 21 (2014) no. 4. doi: 10.37236/4121
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