English

Arithmetical completeness theorems for monotonic modal logics

Logic 2023-04-04 v2

Abstract

We investigate modal logical aspects of provability predicates PrT(x)\mathrm{Pr}_T(x) satisfying the following condition: M\mathbf{M}: If TφψT \vdash \varphi \to \psi, then TPrT(φ)PrT(ψ)T \vdash \mathrm{Pr}_T(\ulcorner \varphi \urcorner) \to \mathrm{Pr}_T(\ulcorner \psi \urcorner). We prove the arithmetical completeness theorems for monotonic modal logics MN\mathsf{MN}, MN4\mathsf{MN4}, MNP\mathsf{MNP}, MNP4\mathsf{MNP4}, and MND\mathsf{MND} with respect to provability predicates satisfying the condition M\mathbf{M}. That is, we prove that for each logic LL of them, there exists a Σ1\Sigma_1 provability predicate PrT(x)\mathrm{Pr}_T(x) satisfying M\mathbf{M} such that the provability logic of PrT(x)\mathrm{Pr}_T(x) is exactly LL. In particular, the modal formulas P\mathrm{P}: ¬\neg \Box \bot and D\mathrm{D}: ¬(A¬A)\neg (\Box A \land \Box \neg A) are not equivalent over non-normal modal logic and correspond to two different formalizations ¬PrT(0=1)\neg \mathrm{Pr}_T(\ulcorner 0=1 \urcorner) and ¬(PrT(φ)PrT(¬φ))\neg \big(\mathrm{Pr}_T(\ulcorner \varphi \urcorner) \land \mathrm{Pr}_T(\ulcorner \neg \varphi \urcorner) \bigr) of consistency statements, respectively. Our results separate these formalizations in terms of modal logic.

Keywords

Cite

@article{arxiv.2208.03555,
  title  = {Arithmetical completeness theorems for monotonic modal logics},
  author = {Haruka Kogure and Taishi Kurahashi},
  journal= {arXiv preprint arXiv:2208.03555},
  year   = {2023}
}

Comments

33 pages

R2 v1 2026-06-25T01:32:20.328Z