The Expressive Power of k-ary Exclusion Logic

In this paper we study the expressive power of k-ary exclusion logic, EXC[k], that is obtained by extending first order logic with k-ary exclusion atoms. It is known that without arity bounds exclusion logic is equivalent with dependence logic. From the translations between them we see that the expressive power of EXC[k] lies in between k-ary and (\(k+1\))-ary dependence logics. We will show that, at least in the case of unary exclusion logic, the both of these inclusions are proper.