Bruhat order on fixed-point-free involutions in the symmetric group
The electronic journal of combinatorics, Tome 21 (2014) no. 2
We provide a structural description of Bruhat order on the set $F_{2n}$ of fixed-point-free involutions in the symetric group $S_{2n}$ which yields a combinatorial proof of a combinatorial identity that is an expansion of its rank-generating function. The decomposition is accomplished via a natural poset congruence, which yields a new interpretation and proof of a combinatorial identity that counts the number of rook placements on the Ferrers boards lying under all Dyck paths of a given length $2n$. Additionally, this result extends naturally to prove new combinatorial identities that sum over other Catalan objects: 312-avoiding permutations, plane forests, and binary trees.
DOI :
10.37236/3861
Classification :
05A19
Mots-clés : Bruhat order, fixed-point-free involutions, Dyck paths, rook placements
Mots-clés : Bruhat order, fixed-point-free involutions, Dyck paths, rook placements
Affiliations des auteurs :
Matthew Watson  1
@article{10_37236_3861,
author = {Matthew Watson},
title = {Bruhat order on fixed-point-free involutions in the symmetric group},
journal = {The electronic journal of combinatorics},
year = {2014},
volume = {21},
number = {2},
doi = {10.37236/3861},
zbl = {1300.05325},
url = {http://geodesic.mathdoc.fr/articles/10.37236/3861/}
}
Matthew Watson. Bruhat order on fixed-point-free involutions in the symmetric group. The electronic journal of combinatorics, Tome 21 (2014) no. 2. doi: 10.37236/3861
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