455 search results - page 3 / 91 » On Trees and Noncrossing Partitions |
COMBINATORICS
1998
13 years 5 months ago
1998
The number of noncrossing partitions of {1, 2, . . . , n} with fixed block sizes has a simple closed form, given by Kreweras, and coincides with the corresponding number for nonne...
DM
2008
13 years 5 months ago
2008
A 2-binary tree is a binary rooted tree whose root is colored black and the other vertices are either black or white. We present several bijections concerning different types of 2...
JCT
2011
13 years 7 days ago
2011
We give combinatorial proofs of the formulas for the number of multichains in the k-divisible noncrossing partitions of classical types with certain conditions on the rank and the ...
DM
2006
13 years 5 months ago
2006
We complete the enumeration of Dumont permutations of the second kind avoiding a pattern of length 4 which is itself a Dumont permutation of the second kind. We also consider some ...
COMBINATORICS
2000
13 years 5 months ago
2000
A (multi)hypergraph H with vertices in N contains a permutation p = a1a2 . . . ak of 1, 2, . . . , k if one can reduce H by omitting vertices from the edges so that the resulting ...