Abstract We describe entailment-preserving translations between two inquisitive systems: the standard system of inquisitive first-order logic InqBQ, which uses a state-based semantic framework, and its team-semantics counterpart, InqBT. By using these translations, we connect some major open problems about these logics, and transfer some recent results about fragments of InqBQ to InqBT.

Abstract Inquisitive modal logic, InqML, is a generalisation of standard Kripke-style modal logic. In its epistemic incarnation, it extends standard epistemic logic to capture not just the information that agents have, but also the questions that they are interested in. Technically, InqML fits within the family of logics based on team semantics. From a model-theoretic perspective, it takes us a step in the direction of monadic second-order logic, as inquisitive modal operators involve quantification over sets of worlds. We introduce and investigate the natural notion of bisimulation equivalence in the setting of InqML. We compare the expressiveness of InqML and first-order logic in the context of relational structures with two sorts, one for worlds and one for information states, and characterise inquisitive modal logic as the bisimulation invariant fragment of first-order logic over various natural classes of two-sorted structures.

This paper investigates a generalized version of inquisitive semantics (Groenendijk, 2008b; Mascarenhas, 2008). A complete axiomatization of the associated logic is established. The connection with intuitionistic logic is clarified and heavily exploited.