Labelled Sequents for Inquisitive First-Order Modal Logic
This work fills a gap by providing a proof system for a logic used to reason about modal dependence and supervenience, which previously lacked one.
The authors provide the first complete labelled sequent calculus for inquisitive first-order modal logic, proving strong completeness and desirable structural properties such as cut admissibility.
In recent work, an inquisitive first-order modal logic has been proposed to reason about relations of modal dependence, including the notion of global supervenience (functional dependence among the extensions of predicates relative to a space of possibilities). At present, no proof system exists for this logic. We provide a complete labelled sequent calculus, extending a calculus developed by Litak and Sano for a weak version of inquisitive first-order logic. We prove strong completeness for the calculus and show that it enjoys desirable structural properties, including the invertibility of its rules and the admissibility of cut.