9 search results - page 2 / 2 » Enumerative combinatorics |
DCG
1999
13 years 5 months ago
1999
Monotone path polytopes arise as a special case of the construction of fiber polytopes, introduced by Billera and Sturmfels. A simple example is provided by the permutahedron, whic...
COMBINATORICS
2006
13 years 5 months ago
2006
A differential poset is a partially ordered set with raising and lowering operators U and D which satisfy the commutation relation DU-UD = rI for some constant r. This notion may ...
JCB
2008
13 years 5 months ago
2008
Abstract. RNA shapes, introduced by Giegerich et al. (17), provide a useful classification of the branching complexity for RNA secondary structures. In this paper, we derive an exa...
JCT
2011
13 years 16 days ago
2011
The Baxter number Bn can be written as Bn = n k=0 Θk,n−k−1 with Θk,ℓ = 2 (k + 1)2 (k + 2) k + ℓ k k + ℓ + 1 k k + ℓ + 2 k . These numbers have first appeared in the...