Control operators.  Linear Logic, by dropping the structural rules of Contraction and Weakening, splits the conjunction ‘&amp;’ of classical logic in a multiplicative and an additive connective.  This move to a resource-sensitive logic can be obtained without sacrificing expressivity: the unary modalities ‘!’,‘?’ allow one to reintroduce Contraction/Weakening in a controlled form and thus to recover classical logic from within the linear setting.