COMBINATORICS
2006
13 years 7 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 7 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 7 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 7 months ago
2006
COMBINATORICS
2006
13 years 7 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 7 months ago
2006
COMBINATORICS
2006
13 years 7 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 7 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 7 months ago
2006
COMBINATORICS
2006
13 years 7 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...