Sur le nombre d'intervalles dans les treillis de Tamari
arXiv:math/0602368
Abstract
We enumerate the intervals in the Tamari lattices. For this, we introduce an inductive description of the intervals. Then a notion of "new interval" is defined and these are also enumerated. A a side result, the inverse of two special series is computed in a group of tree-indexed series.
17 pages, 5 figures