On -bounded families of graphs.
Online coloring known graphs.
On-line 𝓟-coloring of graphs
For a given induced hereditary property 𝓟, a 𝓟-coloring of a graph G is an assignment of one color to each vertex such that the subgraphs induced by each of the color classes have property 𝓟. We consider the effectiveness of on-line 𝓟-coloring algorithms and give the generalizations and extensions of selected results known for on-line proper coloring algorithms. We prove a linear lower bound for the performance guarantee function of any stingy on-line 𝓟-coloring algorithm. In the class of generalized...
On-line list colouring of graphs.
On-line Ramsey theory.
On-line ranking number for cycles and paths
A k-ranking of a graph G is a colouring φ:V(G) → 1,...,k such that any path in G with endvertices x,y fulfilling φ(x) = φ(y) contains an internal vertex z with φ(z) > φ(x). On-line ranking number of a graph G is a minimum k such that G has a k-ranking constructed step by step if vertices of G are coming and coloured one by one in an arbitrary order; when colouring a vertex, only edges between already present vertices are known. Schiermeyer, Tuza and Voigt proved that for n ≥ 2. Here we show...
Optimal Backbone Coloring of Split Graphs with Matching Backbones
For a graph G with a given subgraph H, the backbone coloring is defined as the mapping c : V (G) → N+ such that |c(u) − c(v)| ≥ 2 for each edge {u, v} ∈ E(H) and |c(u) − c(v)| ≥ 1 for each edge {u, v} ∈ E(G). The backbone chromatic number BBC(G,H) is the smallest integer k such that there exists a backbone coloring with maxv∈V (G) c(v) = k. In this paper, we present the algorithm for the backbone coloring of split graphs with matching backbone.
Optimal edge ranking of complete bipartite graphs in polynomial time
An edge ranking of a graph is a labeling of edges using positive integers such that all paths connecting two edges with the same label visit an intermediate edge with a higher label. An edge ranking of a graph is optimal if the number of labels used is minimum among all edge rankings. As the problem of finding optimal edge rankings for general graphs is NP-hard [12], it is interesting to concentrate on special classes of graphs and find optimal edge rankings for them efficiently. Apart from trees...
Orientations and -colourings of graphs
We provide the list of all paths with at most arcs with the property that if a graph admits an orientation such that one of the paths in our list admits no homomorphism to , then is -colourable.
Oriented colouring of some graph products
We obtain some improved upper and lower bounds on the oriented chromatic number for different classes of products of graphs.
Orthogonal art galleries with holes: a coloring proof of Aggarwal's theorem.
Orthogonal colorings of graphs.
Orthogonal partitions and covering of graphs
Orthogonal vector coloring.