Relaxing MIP problem if it is infeasible

Dear GAMS users,

I have a MIP model which I solve in a loop. For some of the points the model becomes infeasible. Instead of interrupting it, however, I want to relax it with RMIP and solve it.



My intention is to do this:



Solve My_Mod using MIP minimizing Obj;

If not feasibile,

Solve My_Mod using RMIP minimizing Obj;



Any help is appreciated.



Yonas


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Yonas,

You can program the if condition based on the model status of your model like this:

Solve My_Mod using MIP minimizing Obj;
if ( My_Mod.modelstat = %ModelStat.Infeasible%
or My_Mod.modelstat = %ModelStat.Integer Infeasible%,
Solve My_Mod using RMIP minimizing Obj;
)

A list of all possible values for modelstat can be found in the Users Guide.

Best regards,
Lutz


On 11/30/2013 11:10 AM, yonas@GMAIL wrote:

Dear GAMS users,

I have a MIP model which I solve in a loop. For some of the points the
model becomes infeasible. Instead of interrupting it, however, I want to
relax it with RMIP and solve it.

My intention is to do this:

Solve My_Mod using MIP minimizing Obj;

If not feasibile,

Solve My_Mod using RMIP minimizing Obj;

Any help is appreciated.

Yonas


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Lutz Westermann LWestermann@gams.com
GAMS Development Corporation GAMS Software GmbH
1217 Potomac St. NW, P.O. Box 40 59
Washington DC, 20007, USA 50216 Frechen, Germany
Fon/Fax: +1 202 342-0180/1 Fon/Fax: +49 221 949-9170/1
http://www.gams.com


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