On the quantified version of the Belnap-Dunn modal logic and some extensions of it

TL;DR

This paper introduces a quantified modal logic extension of Belnap-Dunn logic, proves its strong completeness with respect to possible world semantics, and explores embeddings of Nelson's constructive logics.

Contribution

It develops a quantified version of Belnap-Dunn modal logic, establishes its strong completeness, and embeds Nelson's constructive logics into its extensions.

Findings

Strong completeness of K with expanding domains

Completeness of K with Barcan scheme and constant domains

Faithful embeddings of Nelson's logics into K extensions

Abstract

We consider a quantified version of the (propositional) modal logic $\mathsf{BK}$, proposed earlier by S. P. Odintsov and H. Wansing; this version will be denoted by $\mathsf{QBK}$. Using the canonical model method, we prove the strong completeness of $\mathsf{QBK}$ with respect to a suitable possible world semantics with expanding domains. Similar results are obtained for some natural $\mathsf{QBK}$-extensions. In particular, it is proved that the extension of $\mathsf{QBK}$ with Barcan scheme is strongly complete with respect to a suitable possible world semantics with constant domains. Moreover, we define faithful embeddings (\`a la G\"{o}del-McKinsey-Tarski) of the quantified versions of Nelson's constructive logics into appropriate $\mathsf{QBK}$-extensions.