current bounds on the number of colors: 0 -- 12 Gurobi 5.0.1 (linux64) logging started Sat Dec 15 16:12:43 2012 Optimize a model with 12 rows, 72 columns and 72 nonzeros Presolve removed 12 rows and 72 columns Presolve time: 0.00s Explored 0 nodes (0 simplex iterations) in 0.00 seconds Thread count was 1 (of 16 available processors) Optimal solution found (tolerance 1.00e-04) Best objective 0.000000000000e+00, best bound 0.000000000000e+00, gap 0.0% current bounds on the number of colors: 0 -- 6 Gurobi 5.0.1 (linux64) logging started Sat Dec 15 16:12:43 2012 Optimize a model with 12 rows, 36 columns and 36 nonzeros Presolve removed 12 rows and 36 columns Presolve time: 0.00s Explored 0 nodes (0 simplex iterations) in 0.00 seconds Thread count was 1 (of 16 available processors) Optimal solution found (tolerance 1.00e-04) Best objective 0.000000000000e+00, best bound 0.000000000000e+00, gap 0.0% current bounds on the number of colors: 0 -- 3 Gurobi 5.0.1 (linux64) logging started Sat Dec 15 16:12:43 2012 Optimize a model with 12 rows, 12 columns and 12 nonzeros Presolve removed 12 rows and 12 columns Presolve time: 0.00s Explored 0 nodes (0 simplex iterations) in 0.00 seconds Thread count was 1 (of 16 available processors) Optimal solution found (tolerance 1.00e-04) Best objective 0.000000000000e+00, best bound 0.000000000000e+00, gap 0.0% optimal solution found: number of colors: 1