We present an improved upper bound on the competitiveness of the online coloring algorithm First-Fit in disk graphs which are graphs representing overlaps of disks on the plane. We also show that this bound is best possible for deterministic online coloring algorithms that do not use the disk representation of the input graph. We also present a related new lower bound for unit disk graphs.
['Ioannis Caragiannis', 'Aleksei V. Fishkin', 'Christos Kaklamanis', 'Evi Papaioannou']
A tight bound for online coloring of disk graphs