I was trying to solve a scheduling model using GAMS/Gurobi. The snippet code is:

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```
Binary variable x(i,k);
Equations c1,c2;
c1(k).. sum(i, x(i,k)) =e= 1;
c2(i).. sum(k, x(i,k)) =e= 1;
```

I have used SOS type_1 variables instead of binary variables and run the model.

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```
SOS1 variable x(i,k);
Equations c1,c2;
c1(k).. sum(i, x(i,k)) =e= 1;
c2(i).. sum(k, x(i,k)) =e= 1;
```

AKAIK, the SOS type_1 constraint says that at most one of the variables must be non-zero. the equation is:

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`x1 + x2 + ... + xn <= 1 for n=1...N `

Would you say that do I have a mistake to implement GAMS code, please?the all-zero solution is feasible.

Regards

Omidi. A