科研之友
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摘要
In this paper, a Lebesgue type theorem on the structure of graphs embedded in the surface of characteristic sigma <= 0 is given, that generalizes a result of Borodin on plane graphs. As a consequence, it is proved that every such graph without i-circuits for 4 <= i <= 11-3 sigma is 3-choosable, that offers a new upper bound to a question of Y. Zhao.
- 出版日期2009-1
- 单位南京师范大学
