Title
The Number of Intervals in the m-Tamari Lattices.
Abstract
An m-ballot path of size n is a path on the square grid consisting of north and east steps, starting at (0,0), ending at (mm, n), and never going below the ling {x = my}. The set of these paths can be equipped with a lattice structure, called the m-Tamari lattice and denoted T-n((m)), which generalizes the usual Tamari lattice T-n obtained when m = 1. We prove that the number of intervals in this lattice is m + 1/n(mn + 1)((m + 1)(2)n+m n - 1). This formula was recently conjectured by Bergeronin connection with the study of diagonal coinvariant spaces. The case m = 1 was proved a few years ago by Chapoton. Our proof is based on a recursive description of intervals, which translates into a functional equation satisfied by the associated generating function. The solution of this equation is an algebraic series, obtained by a guess-and-check approach. Finding a bijective proof remains an open problem.
Year
Venue
DocType
2012
ELECTRONIC JOURNAL OF COMBINATORICS
Journal
Volume
Issue
ISSN
18.0
2.0
1077-8926
Citations 
PageRank 
References 
0
0.34
0
Authors
3
Name
Order
Citations
PageRank
Mireille Bousquet-mélou142156.28
Éric Fusy219821.95
Louis-francois Preville-ratelle310.69