On the fractional chromatic number, the chromatic number, and graph products
نویسندگان
چکیده
It is shown that the difference between the chromatic number χ and the fractional chromatic number χf can be arbitrarily large in the class of uniquely colorable, vertex transitive graphs. For the lexicographic product G ◦ H it is shown that χ(G ◦ H) ≥ χf (G)χ(H). This bound has several consequences, in particular it unifies and extends several known lower bounds. Lower bounds of Stahl (for general graphs) and of Bollobás and Thomason (for uniquely colorable graphs) are also proved in a simple, elementary way.
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عنوان ژورنال:
- Discrete Mathematics
دوره 247 شماره
صفحات -
تاریخ انتشار 2002