# Decision Optimization

View Only

## Modify the constraint for infeasiblity

• #### 1.  Modify the constraint for infeasiblity

Posted Tue December 14, 2021 02:39 AM
Hi
I have a model in which constraints are very hard and due to which I am getting infeasible solution and the model (CPLEX) is taking huge amount of time to Solve it.
C0#0: A.0#0 + A.1#1 + A.2#2 + A.3#3 + A.4#4 + A.5#5 + A.6#6 + A.7#7 + A.8#8 = 1
C#1: A.0#0 + A.1#1 + A.2#2 + A.3#3 + A.4#4 + A.5#5 + A.6#6 + A.7#7 + A.8#8  = 2

Is it possible to formulate these constraint in a alternate way that CPLEX can able to find the infeasibility quickly. I tried to use an indicator variable to formulate these equality to inequality constraint but didnt get much difference.

------------------------------
sandeep singh chauhan
------------------------------

Attachment(s)

Model.lp   625 B 1 version

• #### 2.  RE: Modify the constraint for infeasiblity

Posted Wed December 15, 2021 10:27 AM
I'm not sure I understand your need (and the attached model is not clear also), but did you try the feasibility pump heuristic ?https://www.ibm.com/docs/en/icos/20.1.0?topic=parameters-feasibility-pump-switch

------------------------------
Vincent Beraudier
------------------------------

• #### 3.  RE: Modify the constraint for infeasiblity

Posted Mon December 20, 2021 01:45 AM
Hi
Thanks for your response. I am not looking for feasibility pump. Is it possible to find the infeasible solution by changing the constraint. If a + b + c = 2 is modified as (a+b+c) - 2M >= 0 where M is binary variable.

------------------------------
sandeep singh chauhan
------------------------------