Sets, lists and noncrossing partitions
Journal of integer sequences, Tome 11 (2008) no. 1
Partitions of $[n] = {1,2,\dots ,n}$ into sets of lists (A000262) are somewhat less numerous than partitions of $[n]$ into lists of sets (A000670). Here we observe that the former are actually equinumerous with partitions of $[n]$ into lists of $noncrossing$ sets and give a bijective proof. We show that partitions of $[n]$ into sets of noncrossing lists are counted by A088368 and generalize this result to introduce a transform on integer sequences that we dub the "noncrossing partition" transform. We also derive recurrence relations to count partitions of $[n]$ into lists of noncrossing lists.
@article{JIS_2008__11_1_a0,
author = {Callan, David},
title = {Sets, lists and noncrossing partitions},
journal = {Journal of integer sequences},
year = {2008},
volume = {11},
number = {1},
zbl = {1149.05300},
language = {en},
url = {http://geodesic.mathdoc.fr/item/JIS_2008__11_1_a0/}
}
Callan, David. Sets, lists and noncrossing partitions. Journal of integer sequences, Tome 11 (2008) no. 1. http://geodesic.mathdoc.fr/item/JIS_2008__11_1_a0/