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Oriented coloring of 2-outerplanar graphs

Abstract : A graph G is 2-outerplanar if it has a planar embedding such that the subgraph obtained by removing the vertices of the outer face is outerplanar. The oriented chromatic number of an oriented graph H is defined as the minimum order of an oriented graph H' such that H has a homomorphism to H'. In this paper, we prove that 2-outerplanar graphs are 4-degenerate. We also show that oriented 2-outerplanar graphs have a homomorphism to the Paley tournament QR67, which implies that their (strong) oriented chromatic number is at most 67.
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Contributor : Louis Esperet <>
Submitted on : Monday, July 28, 2008 - 6:26:51 PM
Last modification on : Wednesday, November 4, 2020 - 6:08:05 PM
Long-term archiving on: : Friday, November 25, 2016 - 11:23:02 PM


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  • HAL Id : hal-00307156, version 1



Louis Esperet, Pascal Ochem. Oriented coloring of 2-outerplanar graphs. Information Processing Letters, Elsevier, 2007, 101, pp.215--219. ⟨hal-00307156⟩



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