## Decomposing a planar graph of girth 5 into an independent set and a forest

Publication: Research - peer-review › Journal article – Annual report year: 2009

We use a list-color technique to extend the result of Borodin and Glebov that the vertex set of every planar graph of girth at least 5 can be partitioned into an independent set and a set which induces a forest. We apply this extension to also extend Grötzsch's theorem that every planar triangle-free graph is 3-colorable. Let G be a plane graph. Assume that the distance between any two triangles is at least 4. Assume also that each triangle contains a vertex such that this vertex is on the outer face boundary and is not contained in any 4-cycle. Then G has chromatic number at most 3. Note that, in this extension of Grötzsch's theorem an unbounded number of triangles are allowed.

Original language | English |
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Journal | Journal of Combinatorial Theory. Series B |

Volume | 99 |

Issue number | 4 |

Pages (from-to) | 674-684 |

ISSN | 0095-8956 |

DOIs | |

State | Published - 2009 |

Citations | Web of Science® Times Cited: 4 |
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- Forests, Independent sets, Planar graphs of girth 5

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ID: 3420045