  To recover the full expressive power of intuitionistic and classical logic, it is then necessary to add to the MALL fragment two dual modalities, which are usually called exponentials in the linear logic literature. In particular, the “of-course” exponential \(\bang\) permits contraction and weakening to be applied to the formula \(\bang B\) in the left-hand sequent context while the “why-not” exponential \(\quest\) permits contraction and weakening to be applied to the formula \(\quest B\) on the right-hand sequent context. This leads to the full propositional linear logic and to a very nice connection with computer science.