[Scip] scip and zimpl

Bahador Bakhshi bakhshi at gmail.com
Wed Jun 11 13:56:53 MEST 2008


Dear All,

I have a few questions about scip and zimpl, but I'm not sure that I can ask
zimpl related questions in this mailing list (excuse me if I am wrong).

Q1- Why does not zimpl create binary variables when output format is the lp
format?

I have following variable in test.zpl file:

X [F * F] binary;

after creating the test.lp file (zimpl -O test.zpl), I tried to solve the
problem using scip. The output message from scip indicates that there is not
any binary variable. After presolving, all the variables are converted to
binary variables.

I tried the mps output format (zimpl -O -t mps test.zpl). In this case the
original problem has binary variables and presolving consumes less time than
previous case.

Q2-  I ask this question because I am not an expert in Integer programming.
I saw many times in output message from scip that there are non-integral
values in the "dual sol" column. How is it possible to have a non-integral
dual ''intermediate solution'' (before finding the optimal solution) for MIP
problem?

-- 
Best Regards.
---Bahador.
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