It is shown that there is a constant \(c\) such that if \(G\) is a graph embedded in a surface of genus \(g\) (either orientable or non-orientable) and the length of a shortest non-bounding cycle of \(G\) is at least \(c \log (g+1)\), then \(G\) is six-colorable. A similar result holds for three- an
Planar graph colorings without short monochromatic cycles
✍ Scribed by Tomáš Kaiser; Riste Škrekovski
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 126 KB
- Volume
- 46
- Category
- Article
- ISSN
- 0364-9024
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✦ Synopsis
Abstract
It is well known that every planar graph G is 2‐colorable in such a way that no 3‐cycle of G is monochromatic. In this paper, we prove that G has a 2‐coloring such that no cycle of length 3 or 4 is monochromatic. The complete graph K~5~ does not admit such a coloring. On the other hand, we extend the result to K~5~‐minor‐free graphs. There are planar graphs with the property that each of their 2‐colorings has a monochromatic cycle of length 3, 4, or 5. In this sense, our result is best possible. © 2004 Wiley Periodicals, Inc. J Graph Theory 46: 25–38, 2004
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