Skip to content
Preprint

Closure Semantics for Weak Modal Logics: Completeness and Representations

Oct 2026 · 0 citations · 16 references
Mathematics

TL;DR

Close semantics is introduced, a new possible-world semantics for such weak modal logics, and soundness and strong completeness for a range of systems are established.

Abstract

Weak modal logics can be obtained by restricting the axioms and inference rules governing the modal operator. At the extreme, one may consider the least modal logic, in which no specifically modal axiom or inference rule is imposed. We introduce closure semantics, a new possible-world semantics for such weak modal logics, and establish soundness and strong completeness for a range of systems. We also give truth-preserving translations between closure models and other possible-world semantics, including neighborhood, FMT, and Kripke semantics.

View source

Similar papers

Preprint Oct 2026

Modal Extensions of Generalised Nelson Logics

Motivated by relevant epistemic logic, we extend Dunn's simple Kripke-style binary relational semantics for the semi-relevant logic RM to fit a modal extension of RM. It is shown that the modal axioms and rules that need to be added to RM to obtain a sound and complete axiomatisation of its modal extension give an axio...

Igor Sedlár, Pietro Vigiani · 0 citations
Preprint Sep 2026

New Proofs of Weak Normalization for Propositional Logic

New proofs of weak normalization for intuitionistic and classical propositional logics (with the full set of operators -- falsum, implication, conjunction and disjunction) are presented and a deterministic algorithm for weak normalization is presented.

S. Suresh · 0 citations
Preprint Sep 2026

A decision procedure for intuitionistic modal logic IS4 (and IK4)

This paper provides a constructive decision procedure, that, given a formula, produces either a proof showing the formula to be valid or a finite countermodel falsifying the formula, thus also proving the finite model property for both logics.

Marianna Girlando, Roman Kuznets, Sonia Marin et al. · 1 citation
Preprint Sep 2026

Non-elementary modal logics, assuming P $\neq$ NP

It is proved that if a finitely axiomatizable modal logic L is elementary, then the validity problem for L, which asks whether a given finite Kripke frame validates L, is in P, which allows us to transfer complexity results in graph theory to the study of elementarity of modal logics.

Tenyo Takahashi · 0 citations
Conference Open access Sep 2026

Finite Axiomatizability by Disjunctive Existential Rules (Extended Abstract)

In this short paper, we discuss a model-theoretic characterization of when a collection of relational structures is axiomatizable via a finite set of disjunctive existential rules. The presented characterization uses the property of criticality, a refined version of closure under direct products, and a new property tha...

M. Calautti, Marco Console, Andreas Pieris · 0 citations
Preprint Sep 2026

Dynamic Proof Theory for Dynamic Epistemic Logic

This paper proposes a calculus for Dynamic Epistemic Logic (DEL) based on dynamic hypersequents, a new framework for capturing the dynamics of epistemic models in a purely structural and natural way. We enrich dynamic hypersequents with agent indices and an event store, yielding a uniform representation of epistemic ev...

Clara Lerouvillois, F. Poggiolesi · 0 citations

We use cookies to run the site and, with your consent, for analytics and to show ads. See our Cookie Policy.