## Abstract In 1890, Heawood established the upper bound $H ( \varepsilon )= \left \lfloor 7+\sqrt {24\varepsilon +1}/{2}\right \rfloor$ on the chromatic number of every graph embedded on a surface of Euler genus ε ≥ 1. Almost 80 years later, the bound was shown to be tight by Ringel and Youngs. Th
Dirac's map-color theorem for choosability
✍ Scribed by B�hme, T.; Mohar, B.; Stiebitz, M.
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 290 KB
- Volume
- 32
- Category
- Article
- ISSN
- 0364-9024
No coin nor oath required. For personal study only.
✦ Synopsis
It is proved that the choice number of every graph G embedded on a surface of Euler genus ε ≥ 1 and ε = 3 is at most the Heawood number H(ε) = (7 + √ 24ε + 1)/2 and that the equality holds if and only if G contains the complete graph K H(ε) as a subgraph.
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