The maximum possible weight of a fractional clique of a graph is called the fractional clique number of , denoted (Godsil and Royle 2001, pp. 136-137) or (Larson et al. 1995). Every simple graph has a fractional clique number which is a rational number or integer.
The fractional clique number satisfies
where is the clique number, is the fractional chromatic number, and is the chromatic number (Godsil and Royle 2001, pp. 141 and 145), where the result follows from the strong duality theorem for linear programming (Larson et al. 1995; Godsil and Royle 2001, p. 141).