  We study graphon counterparts of the chromatic and the clique number, the
fractional chromatic number, the b-chromatic number, and the fractional clique
number. We establish some basic properties of the independence set polytope in
the graphon setting, and duality properties between the fractional chromatic
number and the fractional clique number. We present a notion of perfect
graphons and characterize them in terms of induced densities of odd cycles and
its complements.
