Geodesic
Analytic determinacy and $0^{\# }$ A forcing-free proof of Harrington’s theorem
Fundamenta Mathematicae, Tome 160 (1999) no. 2, pp. 153-159.

Voir la notice de l'article provenant de la source Institute of Mathematics Polish Academy of Sciences

We prove the following theorem: Given a⊆ω and $1 ≤ α ω_1^{CK}$, if for some $η ℵ_1$ and all u ∈ WO of length η, a is $Σ _α^0(u)$, then a is $Σ_α^0$. We use this result to give a new, forcing-free, proof of Leo Harrington's theorem: $Σ_1^1$-Turing-determinacy implies the existence of $0^#$.
DOI : 10.4064/fm-160-2-153-159

Ramez L. Sami 1

1 
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Ramez L.  Sami. Analytic determinacy and $0^{\# }$ A forcing-free proof of Harrington’s theorem. Fundamenta Mathematicae, Tome 160 (1999) no. 2, pp. 153-159. doi : 10.4064/fm-160-2-153-159. http://geodesic.mathdoc.fr/articles/10.4064/fm-160-2-153-159/

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