 Note that while the local range of a rule or set of rules is a set of valuations, the global range is a set of sets of valuations. But in some cases there is an especially simple relationship between the two, namely that Glo(R) = ℘(Loc(R)). This happens whenever R comprises only zero-premiss rules, and, more interestingly, when the rules in R are interderivable with a set of such rules, given the structural rules (Id), (Weakening), and  (Cut),[14]  as in the case of the natural deduction rules for conjunction R = {(∧I), (∧E)} or the corresponding sequent calculus rules {∧ Right, ∧ Left} where Loc(R) comprises precisely the ∧-Boolean valuations. Evidently, the strong classicality phenomenon of Section  2  is making its presence felt here, and we should contrast the situation with disjunction (in Set-Fmla). For R = {(∨I), (∨E)}, Loc(R) is the class of ∨-Boolean valuations, but the same is the case if (∨E)—the rule of current interest since it has no zero-premiss equivalent—is replaced by another which is far from interderivable with it (even given the structural rules and (∨I)):