I have installed the LP solver Gurobi, and it seems to work successfully work with the vertex_coloring() command. But I wanted to compare runtimes with chromatic_number, and Sage seems to hang whenever I try this.
I construct a graph G, and then when I run the command G.chromatic_number(algorithm="MILP"), Sage hangs. I can tell something has gone wrong because it doesn't come back even when I give it a very small simple graph G, and because Linux tells me that I know have a zombie process.
Any suggestions would be much appreciated.
