Hello Because of the following formula, For D33 ,when (xr+12) > 0, then yr>-∞,and that will cause the following solution to fail. For D11 when (xr+12) > 0,then yr<∞,and that will also cause the following solution to fail.How do I solve this problem, or how do I set limits

You can add a constraint to your AMPL model to set a lower bound or an upper bound on a variable, or on an expression involving variables. For example,

```
s.t. xr_bound {i in D3 union D333, j in IP}:
xr[i,j] + 12 <= 0;
```