COMBINATORICS
2006
13 years 5 months ago
2006
COMBINATORICS
2006
13 years 5 months ago
2006
A "hybrid method", dedicated to asymptotic coefficient extraction in combinatorial generating functions, is presented, which combines Darboux's method and singulari...
COMBINATORICS
2006
13 years 5 months ago
2006
Previous work has shown the perhaps surprising result that, for any binary phylogenetic tree T , there is a set of four characters that define T . Here we deal with the general ca...
COMBINATORICS
2006
13 years 5 months ago
2006
We show that matchings avoiding certain partial patterns are counted by the 3-Catalan numbers. We give a characterization of 12312-avoiding matchings in terms of restrictions on t...
COMBINATORICS
2006
13 years 5 months ago
2006
In two dimensions, a polyform is a finite set of edge-connected cells on a square, triangular, or hexagonal grid. A layer is the set of grid cells that are vertex-adjacent to the ...
COMBINATORICS
2006
13 years 5 months ago
2006
In this paper we study inversions within restricted fillings of Young tableaux. These restricted fillings are of interest because they describe geometric properties of certain sub...
COMBINATORICS
2006
13 years 5 months ago
2006
![Characterization of [1, k]-Bar Visibility Trees](https://www.sciweavers.org/files/imagecache/thumbnail/imagecache/characterization_of_1_k_bar_visibility_trees_COMBINATORICS_2006.jpg "Characterization of [1, k]-Bar Visibility Trees")
A unit bar-visibility graph is a graph whose vertices can be represented in the plane by disjoint horizontal unit-length bars such that two vertices are adjacent if and only if th...
COMBINATORICS
2006
13 years 5 months ago
2006
A simple, undirected 2-connected graph G of order n belongs to class O(n,), 0, if 2 = n - . It is well known (Ore's theorem) that G is hamiltonian if = 0, in which case the 2...
COMBINATORICS
2006
13 years 5 months ago
2006
For n a positive integer, we show that the number of of 2n-tuples of integers that are the row and column sums of some n
COMBINATORICS
2006
13 years 5 months ago
2006
It is proved that, if G is a K4-minor-free graph with maximum degree 4, then G is totally ( + 1)-choosable; that is, if every element (vertex or edge) of G is assigned a list of ...