RLFAP is a real world problem and refers to the allocation of frequencies to radio links. All the instances of the problem involve optimization, some of them are Partial CSPs while others Constrained Optimization Problems. You can get more information and the instances of the problem from Constraints Archive or the CALMA Project.
The best known solutions for all except one of the problem instances are given below. The algorithm used to find these solutions is an extension of GENET network to Partial CSPs and combinatorial optimization.