# a problem with variables in real domains

Hi,

I have a problem with setting the domains of definition of variables.

For example, typing

```
var("y") ; assume(y, "real")
conjugate(y + I)
```

I get the result `y + I`

. The same with `var("y", domain="real")`

.

Where I'm wrong?

thanks!

I am afraid you are not wrong. If we set

`z = y + I`

then`conjugate(z.subs(y=5))`

gives the result`-I + 5`

in contradiction to`conjugate(z).subs(y=5)`

which results to`I + 5`

reported on trac #23135