COMBINATORICS
2002
13 years 4 months ago
2002
A graph is f-choosable if for every collection of lists with list sizes specified by f there is a proper coloring using colors from the lists. The sum choice number is the minimum...
COMBINATORICS
2002
13 years 4 months ago
2002
We present a new expression for the partition function of the dimer arrangements and the Ising partition function of the 3-dimensional cubic lattice. We use the Pfaffian method. T...
COMBINATORICS
2002
13 years 4 months ago
2002
Knowing the excluded minors for a minor-closed matroid property provides a useful alternative characterization of that property. It has been shown in [R. Hall, J. Oxley, C. Semple...
COMBINATORICS
2002
13 years 4 months ago
2002
COMBINATORICS
2002
13 years 4 months ago
2002
We consider Kasteleyn and Kasteleyn-Percus matrices, which arise in enumerating matchings of planar graphs, up to matrix operations on their rows and columns. If such a matrix is ...
COMBINATORICS
2002
13 years 4 months ago
2002
A sequence u = u1u2...un is said to be nonrepetitive if no two adjacent blocks of u are exactly the same. For instance, the sequence abcbcba contains a repetition bcbc, while abca...
COMBINATORICS
2002
13 years 4 months ago
2002
COMBINATORICS
2002
13 years 4 months ago
2002
We give a generalization for the Deza-Frankl-Singhi Theorem in case of multiple intersections. More exactly, we prove, that if H is a set-system, which satisfies that for some k, ...
COMBINATORICS
2002
13 years 4 months ago
2002
COMBINATORICS
2002
13 years 4 months ago
2002