Integer programming 18 Valid inequality Branch-and-cut algorithms 14 Integer programming formulations 12 Graph theory 8 Polytopes 8 Combinatorial optimization 6 Linear programming 6 Polyhedral studies 6 Vertex coloring 6 Vertex coloring problems 6 Adjacent channels 4 Adjacent colors 4 Algorithms 4 Antennas 4 Branch and cut 4 Branch-and-Cut 4 Branch-and-cut 4 Cochannel interference 4 Computational complexity 4 Computational results 4 Computational studies 4 Computer programming 4 Dynamic programming 4 Frequency assignment 4 Frequency assignments 4 Frequency channels 4 Graph multicoloring 4 Heuristic methods 4 Integer programming models 4