Title
On the Number of Edges in Colour-Critical Graphs and Hypergraphs
Abstract
A (hyper)graph G is called k-critical if it has chromatic number k, but every proper sub(hyper)graph of it is (k-1)-colourable. We prove that for sufficiently large k, every k-critical triangle-free graph on n vertices has at least (k-o(k))n edges. Furthermore, we show that every (k+1)-critical hypergraph on n vertices and without graph edges has at least $(k-3/\sqrt[3]{k}) n$ edges. Both bounds differ from the best possible bounds by o(kn) even for graphs or hypergraphs of arbitrary girth.
Year
DOI
Venue
2000
10.1007/s004930070005
Combinatorica
Field
DocType
Volume
Pseudoforest,Discrete mathematics,Combinatorics,Multigraph,Graph power,Gray graph,Cycle graph,Multiple edges,Mathematics,Path graph,Complement graph
Journal
20
Issue
ISSN
Citations 
4
0209-9683
9
PageRank 
References 
Authors
1.20
6
2
Name
Order
Citations
PageRank
Alexandr V. Kostochka168289.87
Michael Stiebitz220730.08