The Galvin-Prikry Theorem in the Weihrauch lattice

Fuente: arXiv
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Main Authors: Marcone, Alberto, Osso, Gian Marco
Format: Preprint
Published: 2024
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author Marcone, Alberto
Osso, Gian Marco
author_facet Marcone, Alberto
Osso, Gian Marco
contents This paper classifies different fragments of the Galvin-Prikry theorem, an infinite dimensional generalization of Ramsey's theorem, in terms of their uniform computational content (Weihrauch degree). It can be seen as a continuation of arXiv:2003.04245v3, which focused on the Weihrauch classification of functions related to the open (and clopen) Ramsey theorem. We show that functions related to the Galvin-Prikry theorem for Borel sets of rank n are strictly between the (n+1)-th and n-th iterate of the hyperjump operator $\mathsf{HJ}$, which is in turn equivalent to the better known $\widehat{\mathsf{WF}}$, which corresponds to $Π^1_1$-$\mathsf{CA}_0$ in the Weihrauch lattice. To establish this classification we obtain the following computability theoretic result: a Turing jump ideal containing homogeneous sets for all $Δ^0_{n+1}(X)$ sets must also contain the n-th hyperjump of X. We also extend our analysis to the transfinite levels of the Borel hierarchy. We further obtain some results about the reverse mathematics of the lightface fragments of the Galvin-Prikry theorem.
format Preprint
id arxiv_https___arxiv_org_abs_2410_06928
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Galvin-Prikry Theorem in the Weihrauch lattice
Marcone, Alberto
Osso, Gian Marco
Logic
03D78, 03B30, 03D30, 05C55
This paper classifies different fragments of the Galvin-Prikry theorem, an infinite dimensional generalization of Ramsey's theorem, in terms of their uniform computational content (Weihrauch degree). It can be seen as a continuation of arXiv:2003.04245v3, which focused on the Weihrauch classification of functions related to the open (and clopen) Ramsey theorem. We show that functions related to the Galvin-Prikry theorem for Borel sets of rank n are strictly between the (n+1)-th and n-th iterate of the hyperjump operator $\mathsf{HJ}$, which is in turn equivalent to the better known $\widehat{\mathsf{WF}}$, which corresponds to $Π^1_1$-$\mathsf{CA}_0$ in the Weihrauch lattice. To establish this classification we obtain the following computability theoretic result: a Turing jump ideal containing homogeneous sets for all $Δ^0_{n+1}(X)$ sets must also contain the n-th hyperjump of X. We also extend our analysis to the transfinite levels of the Borel hierarchy. We further obtain some results about the reverse mathematics of the lightface fragments of the Galvin-Prikry theorem.
title The Galvin-Prikry Theorem in the Weihrauch lattice
topic Logic
03D78, 03B30, 03D30, 05C55
url https://arxiv.org/abs/2410.06928