d-Regular Set Partitions and Rook Placements
Séminaire lotharingien de combinatoire, Tome 62 (2009-2010)
Voir la notice de l'acte provenant de la source Séminaire Lotharingien de Combinatoire website
We use a classical correspondence between set partitions and rook placements on the triangular board to give a quick picture understanding of the "reduction identity"
|P(d)(n,k)| = |P(d-j)(n-j,k-j)|,
where P(d)(n,k) is the collection of all set partitions of [n]:={1,2,...,n} into k blocks such that for any two distinct elements x,y in the same block, we have |y-x| >= d. We also generalize an identity of Klazar on d-regular noncrossing partitions. Namely, we show that the number of d-regular l-noncrossing partitions of [n] is equal to the number of (d-1)-regular enhanced l-noncrossing partitions of [n-1].
@article{SLC_2009-2010_62_a0,
author = {Anisse Kasraoui},
title = {d-Regular {Set} {Partitions} and {Rook} {Placements}},
journal = {S\'eminaire lotharingien de combinatoire},
publisher = {mathdoc},
volume = {62},
year = {2009-2010},
url = {http://geodesic.mathdoc.fr/item/SLC_2009-2010_62_a0/}
}
Anisse Kasraoui. d-Regular Set Partitions and Rook Placements. Séminaire lotharingien de combinatoire, Tome 62 (2009-2010). http://geodesic.mathdoc.fr/item/SLC_2009-2010_62_a0/