English

Filter-induced entailment relations in paraconsistent G\"{o}del logics

Logic 2025-08-12 v2

Abstract

We consider two expansions of G\"{o}del logic G\mathsf{G} with two versions of paraconsistent negation. The first one is Ginv\mathsf{G_{inv}} -- the expansion of G\mathsf{G} with an involuitive negation i{\sim_\mathsf{i}} defined via v(iϕ)=1v(ϕ)v({\sim_\mathsf{i}}\phi)=1-v(\phi). The second one is G(, ⁣<)2\mathsf{G}^2_{(\rightarrow,-\!<)} -- an expansion with a so-called strong negation ¬\neg. This logic utilises two independent valuations on [0,1][0,1] -- v1v_1 (support of truth or positive support) and v2v_2 (support of falsity or negative support) that are connected with ¬\neg. Two valuations in G(, ⁣<)2\mathsf{G}^2_{(\rightarrow,-\!<)} can be combined into one valuation vv on [0,1][0,1]^{\Join} -- the twisted product of [0,1][0,1] with itself -- with two components v1v_1 and v2v_2. The two logics are closely connected as i{\sim_\mathsf{i}} and ¬\neg allow for similar definitions of co-implication -- ϕ ⁣<χ:=i(iχiϕ)\phi-\!<\chi:={\sim_\mathsf{i}}({\sim_\mathsf{i}}\chi\rightarrow{\sim_\mathsf{i}}\phi) and ϕ ⁣<χ:=¬(¬χ¬ϕ)\phi-\!<\chi:=\neg(\neg\chi\rightarrow\neg\phi) -- but do not coincide since the set of values of G(, ⁣<)2\mathsf{G}^2_{(\rightarrow,-\!<)} is not ordered linearly. Our main goal is to study different entailment relations in Ginv\mathsf{G_{inv}} and G(, ⁣<)2\mathsf{G}^2_{(\rightarrow,-\!<)} that are induced by filters on [0,1][0,1] and [0,1][0,1]^{\Join}, respectively. In particular, we determine the exact number of such relations in both cases, establish whether any of them coincide with the entailment defined via the order on [0,1][0,1] and [0,1][0,1]^{\Join}, and obtain their hierarchy. We also construct reductions of filter-induced entailment relations to the ones defined via the order.

Keywords

Cite

@article{arxiv.2405.18262,
  title  = {Filter-induced entailment relations in paraconsistent G\"{o}del logics},
  author = {Sabine Frittella and Daniil Kozhemiachenko},
  journal= {arXiv preprint arXiv:2405.18262},
  year   = {2025}
}
R2 v1 2026-06-28T16:43:59.603Z