  However, not all substructural logics are decidable in this sense. Most famously, the relevant logic \(\mathbf{R}\) is not decidable. This is partly because its proof theory is more complex than that of other substructural logics. \(\mathbf{R}\) differs from linear logic and the Lambek calculus in having a straightforward treatment of conjunction and disjunction. In particular, conjunction and disjunction satisfy the rule of distribution: