COMBINATORICS
2006
13 years 11 months ago
2006
A permutation is said to avoid the permutation if no subsequence in has the same order relations as . Two sets of permutations 1 and 2 are Wilfequivalent if, for all n, the numb...
COMBINATORICS
2006
13 years 11 months ago
2006
We present a variation of James Propp's generalized domino shuffling, which provides an efficient way to obtain perfect matchings of weighted Aztec diamonds. Our modification...
COMBINATORICS
2006
13 years 11 months ago
2006
A graph is Y Y reducible if it can be reduced to isolated vertices by a sequence of series-parallel reductions and Y Y transformations. It is still an open problem to characterize...
COMBINATORICS
2006
13 years 11 months ago
2006
COMBINATORICS
2006
13 years 11 months ago
2006
It is proved that, if G is a K4-minor-free graph with maximum degree 3, then G is totally 4-choosable; that is, if every element (vertex or edge) of G is assigned a list of 4 colo...
COMBINATORICS
2006
13 years 11 months ago
2006
COMBINATORICS
2006
13 years 11 months ago
2006
A proper edge colouring of a graph is neighbour-distinguishing if for all pairs of adjacent vertices v, w the set of colours appearing on the edges incident with v is not equal to...
COMBINATORICS
2006
13 years 11 months ago
2006
In this paper, we study Grothendieck polynomials indexed by Grassmannian permutations from a combinatorial viewpoint. We introduce the factorial Grothendieck polynomials which are...
COMBINATORICS
2006
13 years 11 months ago
2006
COMBINATORICS
2006
13 years 11 months ago
2006
An astral configuration (pq, nk) is a collection of p points and n straight lines in the Euclidean plane where every point has q straight lines passing through it and every line h...