Hierarchical formula classes with respect to semi-classical prenex normalization

Fuente: arXiv
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Autori principali: Fujiwara, Makoto, Kurahashi, Taishi
Natura: Preprint
Pubblicazione: 2025
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author Fujiwara, Makoto
Kurahashi, Taishi
author_facet Fujiwara, Makoto
Kurahashi, Taishi
contents In [10], the authors formalized the standard transformation procedure for prenex normalization of first-order formulas and showed that the classes $\mathrm{E}_k$ and $\mathrm{U}_k$ introduced in Akama et al. [1] are exactly the classes induced by $Σ_k$ and $Π_k$ respectively via the transformation procedure. In that sense, the classes $\mathrm{E}_k$ and $\mathrm{U}_k$ correspond to $Σ_k$ and $Π_k$ based on classical logic respectively. On the other hand, some transformations of the prenex normalization are not possible in constructive theories. In this paper, we introduce new classes $\mathcal{E}_k^n$ and $\mathcal{U}_k^n$ of first-order formulas with two parameters $k$ and $n$, and show that they are exactly the classes induced by $Σ_k$ and $Π_k$ respectively according to the $n$-th level semi-classical prenex normalization, which is obtained by the prenex normalization in [10] with some restriction to the introduced classes of degree $n$. In particular, the latter corresponds to possible transformations in intuitionistic arithmetic augmented with the law-of-excluded-middle schema restricted to formulas of $Σ_n$-form. In fact, if $ n\geq k$, our classes $\mathcal{E}_k^n$ and $\mathcal{U}_k^n$ are identical with the cumulative variants $\mathrm{E}^+_k$ and $\mathrm{U}^+_k$ of $\mathrm{E}_k$ and $\mathrm{U}_k$ respectively. In this sense, our classes are refinements of $\mathrm{E}^+_k$ and $\mathrm{U}^+_k$ with respect to the prenex normalization from the semi-classical perspective.
format Preprint
id arxiv_https___arxiv_org_abs_2506_22348
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Hierarchical formula classes with respect to semi-classical prenex normalization
Fujiwara, Makoto
Kurahashi, Taishi
Logic
03B20, 03F03, 03F50
In [10], the authors formalized the standard transformation procedure for prenex normalization of first-order formulas and showed that the classes $\mathrm{E}_k$ and $\mathrm{U}_k$ introduced in Akama et al. [1] are exactly the classes induced by $Σ_k$ and $Π_k$ respectively via the transformation procedure. In that sense, the classes $\mathrm{E}_k$ and $\mathrm{U}_k$ correspond to $Σ_k$ and $Π_k$ based on classical logic respectively. On the other hand, some transformations of the prenex normalization are not possible in constructive theories. In this paper, we introduce new classes $\mathcal{E}_k^n$ and $\mathcal{U}_k^n$ of first-order formulas with two parameters $k$ and $n$, and show that they are exactly the classes induced by $Σ_k$ and $Π_k$ respectively according to the $n$-th level semi-classical prenex normalization, which is obtained by the prenex normalization in [10] with some restriction to the introduced classes of degree $n$. In particular, the latter corresponds to possible transformations in intuitionistic arithmetic augmented with the law-of-excluded-middle schema restricted to formulas of $Σ_n$-form. In fact, if $ n\geq k$, our classes $\mathcal{E}_k^n$ and $\mathcal{U}_k^n$ are identical with the cumulative variants $\mathrm{E}^+_k$ and $\mathrm{U}^+_k$ of $\mathrm{E}_k$ and $\mathrm{U}_k$ respectively. In this sense, our classes are refinements of $\mathrm{E}^+_k$ and $\mathrm{U}^+_k$ with respect to the prenex normalization from the semi-classical perspective.
title Hierarchical formula classes with respect to semi-classical prenex normalization
topic Logic
03B20, 03F03, 03F50
url https://arxiv.org/abs/2506.22348