English

Very weak subintuitionistic logics

Logic 2026-05-21 v1

Abstract

We introduce a new propositional logic, called very weak subintuitionistic logic VF\mathbf{VF}, by adapting the relational semantics of Fitting, Marek, and Truszczy\'nski for the pure logic of necessitation N\mathbf{N} to the propositional setting. We prove that VF\mathbf{VF} and its closed negative extensions are sound and complete with respect to this semantics, and that they have the disjunction property and the finite frame property. We also prove that VF\mathbf{VF} is strictly weaker than the weak subintuitionistic logic WF\mathbf{WF} of Shirmohammadzadeh Maleki and de Jongh. Finally, we study modal companions of VF\mathbf{VF} and its closed negative extensions via Corsi's modified G\"odel translation.

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Cite

@article{arxiv.2605.20769,
  title  = {Very weak subintuitionistic logics},
  author = {Taishi Kurahashi and Mashu Noguchi},
  journal= {arXiv preprint arXiv:2605.20769},
  year   = {2026}
}

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22 pages