On the complexity of input/output logic

Input/output logic is a formalism in deontic logic and normative reasoning. Unlike deontic logical frameworks based on possible-world semantics, input/output logic adopts norm-based semantics in the sense of [13], specifically operational semantics. It is well-known in theoretical computer science that complexity is an indispensable component of every logic. So far, previous literature in input/output systems focuses on proof theory and semantics, while neglects complexity. This paper adds the missing component by giving the complexity results of main decision problems in input/output logic. Our results show that input/output logic is coNP hard and in the 2nd level of the polynomial hierarchy.