These formulations do appear to be the same, except that in the constraint you should say “if m in {10,11,12,1,2,3,4}”. But I think you could express the model even more clearly like this:

```
set MESES;
set MESES_A_SJ_P within MESES;
var AREA_SOJA {MESES};
var A_SJ_P >= 0;
s.t. SOJA_PLANTADA {m in MESES}:
AREA_SOJA[m] = if m in MESES_A_SJ_P then A_SJ_P else 0;
```

Then in a data file for this model, you could specify the members of the two sets with the following statements:

```
set MESES := OUT NOV DEZ JAN FEV MAR ABR MAI JUN JUL AGO SET ;
set MESES_A_SJ_P := OUT NOV DEZ JAN FEV MAR ABR ;
```

I am not sure why you need to have the set JANEIRO. Is there some other constraint in the model where you need the months to be given by numbers?