1. The problem statement, all variables and given/known data Express each of these system specifications using predicates, quantifiers, and logical connectives, if necessary. a) Every user has access to exactly one mailbox. 2. Relevant equations 3. The attempt at a solution It is typical of my book to not answer questions as given with the unique existential quantifier [itex]\exists ![/itex]. For instance, the answer to the question above is [itex]∀u∃m(A(u, m)∧∀n(n \ne m→¬A(u, n)))[/itex]. However, I am not convinced that this form assures that only one m exists for every u. Isn't it still possible that [itex]m_0[/itex] and[itex]m_1[/itex] are two elements in the domain of the variable that make the statement, implying that there doesn't exists one and only one value of m for every u?