I need help in the following problem:

Let be a (first order) language. Find -fomulae that for any -structure with support :

.

Some ideas: Because the signature is empty, there are no relations, no functions and no constants. The only possible formulae consist of terms like with variables and the logical signs (,), (others excluded by demand).

For I guess something like:

but this seems quite complex. Is there a shorter form? Or is it even correct? And the others?