Title
Uniquely (m,k)&tgr;-colourable graphs and k—&tgr;-saturated graphs
Abstract
For a graph G, the path number tau(G) is defined as the order of a longest path in G. An (m, k)(tau)-colouring of a graph H is a partition of the vertex set of H into in subsets such that each subset induces a subgraph of H for which tau is at most k. The k-tau-chromatic number chi(k)(tau)(H) is the least in for which H has an (m, k)(tau)-colouring. A graph H is uniquely (m, k)(tau)-colourable if chi(k)(tau)(H)=m and there is only one partition of the vertex set of H which is an (m, k)(tau)-colouring of H. A graph G is called k-tau-saturated if tau(G)less than or equal to k and tau(G+e)greater than or equal to k+1 for all e is an element of(<E(G)over bar>). For k=1, the graphs obtained by taking the join of k-tau-saturated graphs (which are empty graphs in this case) are known to be uniquely colourable graphs. In this paper we construct uniquely (m, k)(tau)-colourable graphs (for all positive integers m and k) using k-tau-saturated graphs in a similar fashion. As a corollary we characterise those p for which there exists a uniquely (m, k)(tau)-colourable graph of order p.
Year
DOI
Venue
1996
10.1016/0012-365X(95)00301-C
Discrete Mathematics
Keywords
DocType
Volume
colourable graph,longest path
Journal
162
Issue
ISSN
Citations 
1-3
0012-365X
0
PageRank 
References 
Authors
0.34
0
4
Name
Order
Citations
PageRank
Gerhard Benadé100.34
Izak Broere214331.30
Betsie Jonck300.34
Marietjie Frick419133.21