9 years 6 months ago
A study of 3-arc graphs
An arc of a graph is an oriented edge and a 3-arc is a 4-tuple (v, u, x, y) of vertices such that both (v, u, x) and (u, x, y) are paths of length two. The 3-arc graph of a graph ...
Martin Knor, Guangjun Xu, Sanming Zhou
137views more  ALGORITHMICA 2010»
9 years 10 months ago
Deciding k-Colorability of P5-Free Graphs in Polynomial Time
The problem of computing the chromatic number of a P5-free graph (a graph which contains no path on 5 vertices as an induced subgraph) is known to be NP-hard. However, we show tha...
Chính T. Hoàng, Marcin Kaminski, Vad...
149views more  MP 2010»
9 years 10 months ago
Copositive programming motivated bounds on the stability and the chromatic numbers
The Lov´asz theta number of a graph G can be viewed as a semidefinite programming relaxation of the stability number of G. It has recently been shown that a copositive strengthe...
Igor Dukanovic, Franz Rendl
135views more  JGT 2010»
9 years 10 months ago
Cycle length parities and the chromatic number
In 1966 Erd˝os and Hajnal proved that the chromatic number of graphs whose
Christian Löwenstein, Dieter Rautenbach, Ingo...
117views more  JGT 2010»
9 years 10 months ago
An approximate version of Hadwiger's conjecture for claw-free graphs
Hadwiger’s conjecture states that every graph with chromatic number χ has a clique minor of size χ. In this paper we prove a weakened version of this conjecture for the class ...
Maria Chudnovsky, Alexandra Ovetsky Fradkin
118views more  DM 1998»
9 years 11 months ago
Chromatic Ramsey numbers
Suppose G is a graph. The chromatic Ramsey number rc(G) of G is the least integer m such that there exists a graph F of chromatic number m for which the following is true: For any...
Xuding Zhu
186views more  DM 2002»
9 years 11 months ago
Coloring Eulerian triangulations of the projective plane
A simple characterization of the 3, 4, or 5-colorable Eulerian triangulations of the projective plane is given. Key words: Projective plane, triangulation, coloring, Eulerian grap...
Bojan Mohar
121views more  ENDM 2000»
9 years 11 months ago
Finding the chromatic number by means of critical graphs
We propose a new exact algorithm for finding the chromatic number of a graph G. The algorithm attempts to determine the smallest possible induced subgraph G' of G which has t...
Francine Herrmann, Alain Hertz
150views more  DM 2000»
9 years 11 months ago
A note on generalized chromatic number and generalized girth
Erdos proved that there are graphs with arbitrarily large girth and chromatic number. We study the extension of this for generalized chromatic numbers. Generalized graph coloring d...
Béla Bollobás, Douglas B. West
175views more  ARSCOM 2004»
9 years 11 months ago
Circular Chromatic Number of Hypergraphs
The concept of circular chromatic number of graphs was introduced by Vince(1988). In this paper we define circular chromatic number of uniform hypergraphs and study their basic pr...
Changiz Eslahchi, Arash Rafiey