liu heng
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Latest activity by liu heng
liu heng created a post,
About PoolSearchMode
AnsweredHow can I collect a rich set of feasible solutions (both highquality and bad ones). It seems like PoolSearchMode=2 does not collect bad solutions while PoolSearchMode=1 does not collect the good o...

liu heng commented,
Thanks a lot! Can I just assume that when I call p = m.presolve(), then p and m are independent, modifications on either model will not affect the other?

liu heng created a post,
Does modification on presolved model affect original model?
AnsweredSuppose m is the original model and p = m.presolve() If I do some modifications on p (e.g. optimize or modify variable bounds), will the original model be modified?

liu heng commented,
This is much faster, thanks a lot!

liu heng commented,
Thank you Riley, I have tried this but there is still some issues: replace_fixings(m) spent much more time than m.presolve() (in fact my model has much more than 100 variables), I wonder if there i...

liu heng created a post,
How to stop presolve from removing variables
AnsweredAssume the original model m has 100 variables, and I fix 30 of the 100 variables by setting v.UB=1 , v.LB=1. I want to get the corresponding model with 70 variables. However, if I call p=m.presolve...

liu heng created a post,
How to compute the objective and feasibility of a manually given solution?
AnsweredSuppose "sol" is a list that consists of the value of each variable.(sol is given by user) How to compute the objective and feasiblity of sol

liu heng created a post,
How to check the feasibility of a certain solution
AnsweredSuppose I manually give a solution by setting v.Start = xxx. Then I call m.optimize() and the log only shows that "Loaded user MIP start with objective xxx". Does it means the solution is feasible?

liu heng created a post,
How do Precrush and AggFill/Aggregate affect variables
AnsweredHow do Precrush and AggFill/Aggregate affect variables?(introduce new vars or remove vars)

liu heng commented,
Thank you Michel, but if call reduced_model=model.presolve(), the solution of 'reduced_model' cannot be mapped back to the solution of 'model'