Let r(G) denote the rank of the adjacency matrix of a graph G. When a vertex and its incident edges are deleted from G, the rank of the resultant graph cannot exceed r(G) and can decrease by at most 2. The problem of determining the exact effect of adding a single vertex to a graph is more difficult
On vertex ranking of a starlike graph
β Scribed by Sun-yuan Hsieh
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 76 KB
- Volume
- 82
- Category
- Article
- ISSN
- 0020-0190
No coin nor oath required. For personal study only.
β¦ Synopsis
A vertex coloring c : V β {1, 2, . . . , t} of a graph G = (V , E) is a vertex t-ranking if for any two vertices of the same color every path between them contains a vertex of larger color. The vertex ranking number Ο r (G) is the smallest value of t such that G has a vertex t-ranking. A Ο r (G)-ranking of G is said to be an optimal vertex ranking. In this paper, we present an O(|V | + |E|) time algorithm for finding an optimal vertex ranking of a starlike graph G = (V , E). Our result implies that an optimal vertex ranking of a split graph can be computed in linear time.
π SIMILAR VOLUMES
## Abstract We prove in this note that the linear vertexβarboricity of any planar graph is at most three, which confirms a conjecture due to Broere and Mynhardt, and others.
Lawrence [2, Theorem 3] and Borodin and Kostochka [1, Lemma 2' 1 both give the same theorem about vertex colorings of graphs (Corollary 1 below). But Lawrence's proof, although powerful, is a little long, and Borodin and Kostoehka state the result without a proof.
Let D be an oriented graph of order n β₯ 9, minimum degree at least n -2, such that, for the choice of distinct vertices x and y, . Graph Theory 18 (1994), 461-468) proved that D is pancyclic. In this note, we give a short proof, based on Song's result, that D is, in fact, vertex pancyclic. This also
Wiseman, J.A., On the intersection rank of a graph, Discrete Mathematics 104 293-305.