Title
On the Strong Chromatic Number of Graphs
Abstract
The strong chromatic number, $\chi_S(G)$, of an $n$-vertex graph $G$ is the smallest number $k$ such that after adding $k\lceil n/k\rceil - n$ isolated vertices to $G$ and considering any partition of the vertices of the resulting graph into disjoint subsets $V_1, \ldots, V_{\lceil n/k\rceil}$ of size $k$ each, one can find a proper $k$-vertex-coloring of the graph such that each part $V_i$, $i=1, \ldots, \lceil n/k\rceil$, contains exactly one vertex of each color. For any graph $G$ with maximum degree &Dgr;, it is easy to see that $\chi_S(G) \geq \Delta + 1$. Recently, Haxell proved that $\chi_S(G) \leq 3\Delta - 1$. In this paper, we improve this bound for graphs with large maximum degree. We show that $\chi_S(G) \leq 2\Delta$ if $\Delta \geq n/6$ and prove that this bound is sharp.
Year
DOI
Venue
2006
10.1137/050633056
SIAM J. Discrete Math.
Keywords
Field
DocType
isolated vertex,maximum degree,geq n,lceil n,strong chromatic number,disjoint subsets,large maximum degree,resulting graph,smallest number,vertex graph,transversals
Discrete mathematics,Graph,Combinatorics,Disjoint sets,Vertex (geometry),Chromatic scale,Vertex (graph theory),Transversal (geometry),Degree (graph theory),Partition (number theory),Mathematics
Journal
Volume
Issue
ISSN
20
3
SIAM J. Discrete Math. 20(3) (2006), 741--747
Citations 
PageRank 
References 
5
0.55
4
Authors
2
Name
Order
Citations
PageRank
Maria Axenovich120933.90
Ryan Martin214414.43