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Main Authors: Bonzio, Stefano, Zamperlin, Nicolò
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2403.01274
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author Bonzio, Stefano
Zamperlin, Nicolò
author_facet Bonzio, Stefano
Zamperlin, Nicolò
contents Weak Kleene logics are three-valued logics characterized by the presence of an infectious truth-value. In their external versions, as they were originally introduced by Bochvar and Hallden, these systems are equipped with an additional connective capable of expressing whether a formula is classically true. In this paper we further expand the expressive power of external weak Kleen logics by modalizing them with a unary operator. The addition of an alethic modality gives rise to the two systems $\B^{\square}$ and $MPWK$, which have two different readings of the modal operator. We provide these logics with a complete and decidable Hilbert-style axiomatization w.r.t. a three-valued possible worlds semantics. The starting point of these calculi are new axiomatizations for the non-modal bases B and PWKe, which we provide using the recent algebraization results about these two logics. In particular, we prove the algebraizability of $\PWKe$. Finally some standard extensions of the basic modal systems are provided with their completeness results w.r.t. special classes of frames.
format Preprint
id arxiv_https___arxiv_org_abs_2403_01274
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Modal weak Kleene logics: axiomatizations and relational semantics
Bonzio, Stefano
Zamperlin, Nicolò
Logic
03B45
Weak Kleene logics are three-valued logics characterized by the presence of an infectious truth-value. In their external versions, as they were originally introduced by Bochvar and Hallden, these systems are equipped with an additional connective capable of expressing whether a formula is classically true. In this paper we further expand the expressive power of external weak Kleen logics by modalizing them with a unary operator. The addition of an alethic modality gives rise to the two systems $\B^{\square}$ and $MPWK$, which have two different readings of the modal operator. We provide these logics with a complete and decidable Hilbert-style axiomatization w.r.t. a three-valued possible worlds semantics. The starting point of these calculi are new axiomatizations for the non-modal bases B and PWKe, which we provide using the recent algebraization results about these two logics. In particular, we prove the algebraizability of $\PWKe$. Finally some standard extensions of the basic modal systems are provided with their completeness results w.r.t. special classes of frames.
title Modal weak Kleene logics: axiomatizations and relational semantics
topic Logic
03B45
url https://arxiv.org/abs/2403.01274