Graph minors: X. obstructions to tree-decomposition
Journal of Combinatorial Theory Series B
Discrete Applied Mathematics - Special issue: efficient algorithms and partial k-trees
Colored homomorphisms of colored mixed graphs
Journal of Combinatorial Theory Series B
Discrete Mathematics
Journal of Combinatorial Theory Series B
DAG-width: connectivity measure for directed graphs
SODA '06 Proceedings of the seventeenth annual ACM-SIAM symposium on Discrete algorithm
Tree-depth, subgraph coloring and homomorphism bounds
European Journal of Combinatorics
Digraph measures: Kelly decompositions, games, and orderings
Theoretical Computer Science
Better Polynomial Algorithms on Graphs of Bounded Rank-Width
Combinatorial Algorithms
On Digraph Width Measures in Parameterized Algorithmics
Parameterized and Exact Computation
STACS'06 Proceedings of the 23rd Annual conference on Theoretical Aspects of Computer Science
Oriented coloring: complexity and approximation
SOFSEM'06 Proceedings of the 32nd conference on Current Trends in Theory and Practice of Computer Science
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Oriented colouring is a quite intuitive generalization of undirected colouring, yet the problem remains NP-hard even on digraph classes with bounded usual directed width measures. In light of this fact, one might ask whether new width measures are required for efficient dealing with this problem or whether further restriction of traditional directed width measures such as DAG-width would suffice. The K-width and DAG-depth measures (introduced by [Ganian et al, IWPEC'09]) are ideal candidates for tackling this question: They are both closely tied to the cops-and-robber games which inspire and characterize the most renowned directed width measures, while at the same time being much more restrictive.In this paper, we look at the oriented colouring problem on digraphs of bounded K-width and of bounded DAG-depth. We provide new polynomial algorithms for solving the problem on "small" instances as well as new strong hardness results showing that the input restrictions required by our algorithms are in fact "tight".