Homomorphisms to oriented paths
β Scribed by Pavol Hell; Xuding Zhu
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 523 KB
- Volume
- 132
- Category
- Article
- ISSN
- 0012-365X
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π SIMILAR VOLUMES
W. Gutjahr, E. Welzl, and G. Woeginger have given a polynomial time algorithm to decide whether a given digraph is homomorphic to an oriented path. The corresponding problem for oriented cycles (i.e., given a digraph \(G\), is it homomorphic to a fixed oriented cycle \(C\) ?) remained open. We prove
## Abstract There are three types of oriented 2βpaths. Necessary and sufficient conditions are given under which all oriented 2βpaths of the same type and with vertices labeled 1, 2,β¦., __n__ can be partitioned into copies of the complete symmetric directed graph with __n__ vertices.
## Abstract If ${\cal C}$ is a class of oriented graphs (directed graphs without opposite arcs), then an oriented graph is a __homomorphism bound__ for ${\cal C}$ if there is a homomorphism from each graph in ${\cal C}$ to __H__. We find some necessary conditions for a graph to be a homomorphism bo
## Abstract We investigate bounds on the chromatic number of a graph __G__ derived from the nonexistence of homomorphisms from some path \documentclass{article}\footskip=0pc\pagestyle{empty}\begin{document}\begin{eqnarray\*}\vec{P}\end{eqnarray\*}\end{document} into some orientation \documentclass{