Finite Combinatorics and Fragments of Arithmetic

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1. Verfasser: Wang, Wei
Format: Preprint
Veröffentlicht: 2025
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author Wang, Wei
author_facet Wang, Wei
contents In fragments of first order arithmetic, definable maps on finite domains could behave very differently from finite maps. Here combinatorial properties of $Σ_{n+1}$-definable maps on finite domains are compared in the absence of $BΣ_{n+1}$. It is shown that $\mathrm{GPHP}(Σ_{n+1})$ (the $Σ_{n+1}$-instance of Kaye's General Pigeonhole Principle) lies strictly between $\mathrm{CARD}(Σ_{n+1})$ and $\mathrm{WPHP}(Σ_{n+1})$ (Weak Pigeonhole Principle for $Σ_{n+1}$-maps), and also that $\mathrm{FRT}(Σ_{n+1})$ (Finite Ramsey's Theorem for $Σ_{n+1}$-maps) does not imply $\mathrm{WPHP}(Σ_{n+1})$.
format Preprint
id arxiv_https___arxiv_org_abs_2506_17943
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Finite Combinatorics and Fragments of Arithmetic
Wang, Wei
Logic
03F30, 03C20, 03H15
In fragments of first order arithmetic, definable maps on finite domains could behave very differently from finite maps. Here combinatorial properties of $Σ_{n+1}$-definable maps on finite domains are compared in the absence of $BΣ_{n+1}$. It is shown that $\mathrm{GPHP}(Σ_{n+1})$ (the $Σ_{n+1}$-instance of Kaye's General Pigeonhole Principle) lies strictly between $\mathrm{CARD}(Σ_{n+1})$ and $\mathrm{WPHP}(Σ_{n+1})$ (Weak Pigeonhole Principle for $Σ_{n+1}$-maps), and also that $\mathrm{FRT}(Σ_{n+1})$ (Finite Ramsey's Theorem for $Σ_{n+1}$-maps) does not imply $\mathrm{WPHP}(Σ_{n+1})$.
title Finite Combinatorics and Fragments of Arithmetic
topic Logic
03F30, 03C20, 03H15
url https://arxiv.org/abs/2506.17943