Hi,

I defined a set and a parameter as

```
Sets i /1, 2/;
Positive Variable X_V_ce(i);
```

one of the constraints is

```
Z1(i).. X_V_ce(i) =e= X_V_ce(i+1) + ....
```

How it can be defined, i cannot be set i+1 !!

What can I do to add 1 or 2 to an element?

Regards

Renger
2
Hi

This is not a problem for Gams. For i = 2, it writes the equation as

Z1(i)… X_V_ce(“2”) =e= 0;

If you want another formulation for this case, you could use the cardinality of set i (the number of elements):

Z1(i)… X_V_ce(i) =e= X_V_ce(i+1)(ord(i) ne card(i) + (.....)(ord(i) eq card(i);

Hope this answers your question

Cheers

Renger