Hello everyone,
I'm running a huge MIP model (minimization problem) using Gurobi 7.0. I notice that during the optimization process Gurobi expends a lot of time in the root node with no changes in the lower bound. So, I decided to play with Cuts and CutPasses parameters (GRB_IntParam_Cuts and/or GRB_IntParam_CutPasses).
I attached 4 .log files, namely:
-Log_1.log: with Cuts and CutsPasses enabled, with default values (-1).
-Log_2.log: with Cuts set to 0 (disabled) and CutPasses enabled, as default.
-Log_3.log: with Cuts and CutPasses, both, set to 0 (disabled).
-Log_4.log: same configuration as Log_3.log, bus with a time limit of 7200s.
By comparing Log_1 with Log_3 (and Log_4), one can see that, surprisingly, without CutPasses Gurobi run slower (reaches the time limit at the root node) than the version with it enabled (finds the opt solution at node 48). Almost the same situation can be seen when comparing Log_2 with Log_3 (and Log_4).
Also, in Log_4.log, without both Cuts and CutPasses (should run faster) after more than 7000s gurobi still in the root node.
Is this behaviour normal? Is there any explanation for that?
Thank you,
Arthur