Originally posted by: bengu1

Hi,

I am using Java concert, and in the current setup only 30 minutes are allowed for a MIP run. Whenever a MIP model takes longer then 30 mins, then I want to add a preprocessing step (set symmetry to 5) and rerun the model from scratch. I am able to add the parameter after 30 minutes and run it, however it continues from the node where it stopped. Also, I dont want to put symmetry parameter upfront since it will affect all other runs ( interested in using this parameter only when it is not able to find a good solution even after 30 mins ).How do I accomplish this ?.

Thanks in advance.

Regards,

Saran. 

If you turn off the advanced start switch parameter (i.e., set it to zero), the model should run from scratch when running the second time.

Originally posted by: bengu1

Thanks alot. Also, if I use repeatpresolve parameter then will it do a presolve again at the current node before preceding with branch and cut process ?. Thanks.

By default, it should repeat presolve (i.e., you shouldn't have to modify the MIP repeat presolve switch parameter to get this behavior). I ran a quick sanity test in the interactive, and you can see this in the log file.