I got in my problem some binary variable, thats a decision to install or not an equipment in a house. Among a lot of other variables and constraints, my problem is something like this:

```
N = 5; # number of houses
@variable(m, a[i=1:N], Bin)
@objective(m, Min, sum(a[i] for i = 1:N))
```

But for a larger N (around `30+`

), the problem gets to big to be solved in an acceptable time (using a Branch-and-Bound solver).

So, to reduce the number of binary variables, i was thinking in just choose some `a[i]`

to be binary. For example, binary for `i = 2:3`

:

`@variable(m, a[i=2:3], Bin)`

But i’m getting this error:

`ERROR: LoadError: Failed attempt to index JuMPArray along dimension 1: 1 ∉ 2:3`

Does anyone knows any trick in how work around this?