- List edge-coloring
In
mathematics , list edge-coloring is a type ofgraph coloring .More precisely, a list edge-coloring is a "choice function" that maps every edge to a color from a prescribed list for that edge.A graph is "k"-edge-choosable if it has a proper list edge-coloring - one in which no two adjacent edges receive the same color - for every collection of lists of k colors.The edge choosability, or "list edge colorability", "list edge chromatic number", or "list chromatic index", ch′("G") of a graph "G" is the least number "k" such that "G" is "k"-edge-choosable.Some properties of ch′("G"):
# ch′("G") < 2 χ′("G").
# ch′(K"n","n") = "n". (Galvin 1995)
# ch′("G") < (1 + o(1))χ′("G"), i.e. the list chromatic index and the chromatic index agree asymptotically. (Kahn 2000)Here χ′("G") is the chromatic index of "G"; and K"n","n", the complete bipartite graph with equal partite sets.The most famous open problem about list edge-coloring is probably the "list coloring conjecture".
List coloring conjecture.:ch′("G") = χ′("G").
This conjecture has a fuzzy origin.Interested readers are directed to
[Jensen, Toft 1995] for an overview of its history.It is also a generalization of the longstandingDinitz conjecture , which was eventually solved by Galvin in 1995 using list edge-coloring.See also
*
List coloring
*Edge coloring References
* Galvin, Fred (1995). The list chromatic index of a bipartite multigraph. "J. Combin. Theory (B)" 63, 153–158.
* Jensen, Tommy R.; Toft, Bjarne (1995). "Graph coloring problems". New York: Wiley-Interscience. ISBN 0-471-02865-7.
* Kahn, Jeff (2000). Asymptotics of the list chromatic index for multigraphs. "Rand. Struct. Alg." 17, 117–156.
Wikimedia Foundation. 2010.