منابع مشابه
Circular choosability
We study circular choosability, a notion recently introduced by Mohar and by Zhu. First, we provide a negative answer to a question of Zhu about circular cliques. We next prove that cch(G) = O (ch(G) + ln |V (G)|) for every graph G. We investigate a generalisation of circular choosability, the circular f -choosability, where f is a function of the degrees. We also consider the circular choice n...
متن کاملCircular choosability of graphs
This paper discusses the circular version of list coloring of graphs. We give two definitions of the circular list chromatic number (or circular choosability) of a graph and prove that they are equivalent. Then we prove that for any graph , . Examples are given to show that this bound is sharp in the sense that for any , there is a graph with . It is also proved that -degenerate graphs have . T...
متن کاملCircular Degree Choosability
We extend a characterization of degree-choosable graphs due to Borodin [1], and Erdős, Rubin and Taylor [2], to circular list-colorings.
متن کاملCircular choosability is rational
The circular choosability or circular list chromatic number of a graph is a list-version of the circular chromatic number, introduced by Mohar [4] and studied in [17, 2, 5, 7, 8, 15] and [10]. One of the nice properties that the circular chromatic number enjoys is that it is a rational number for all finite graphs G (see for instance [16]), and a fundamental question, posed by Zhu [17] and reit...
متن کاملCircular choosability via combinatorial Nullstellensatz
A p-list assignment L of a graph G assigns to each vertex v of G a set L(v) ⊆ {0, 1, . . . , p − 1} of permissible colors. We say G is L-(p, q)-colorable if G has a (p, q)-coloring h such that h(v) ∈ L(v) for each vertex v. The circular list chromatic number χc,l(G) of a graph G is the infimum of those real numbers t for which the following holds: For any p, q, for any p-list assignment L with ...
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ژورنال
عنوان ژورنال: Journal of Graph Theory
سال: 2009
ISSN: 0364-9024,1097-0118
DOI: 10.1002/jgt.20375