Published online by Cambridge University Press: 19 September 2016
The classical theorem of Vizing states that every graph of maximum degree $d$ admits an edge coloring with at most
$d+1$ colors. Furthermore, as it was earlier shown by Kőnig,
$d$ colors suffice if the graph is bipartite. We investigate the existence of measurable edge colorings for graphings (or measure-preserving graphs). A graphing is an analytic generalization of a bounded-degree graph that appears in various areas, such as sparse graph limits, orbit equivalence and measurable group theory. We show that every graphing of maximum degree
$d$ admits a measurable edge coloring with
$d+O(\sqrt{d})$ colors; furthermore, if the graphing has no odd cycles, then
$d+1$ colors suffice. In fact, if a certain conjecture about finite graphs that strengthens Vizing’s theorem is true, then our method will show that
$d+1$ colors are always enough.