The equivalence of determinacy and iterated sharps
We characterize, in terms of determinacy, the existence of 0♯♯ as well as the existence of each of the following: 0♯♯♯, 0♯♯♯♯,0♯♯♯♯♯, ... For k ∈ ω, we define two classes of sets, (k * Σ01)* and (k * Σ01)*+, which lie strictly between $\bigcup_{\beta < \omega^2}(\beta-\Pi^1_1)$ and Δ(ω2-Π11). We...
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Veröffentlicht in: | The Journal of symbolic logic 1990-06, Vol.55 (2), p.502-525 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | We characterize, in terms of determinacy, the existence of 0♯♯ as well as the existence of each of the following: 0♯♯♯, 0♯♯♯♯,0♯♯♯♯♯, ... For k ∈ ω, we define two classes of sets, (k * Σ01)* and (k * Σ01)*+, which lie strictly between $\bigcup_{\beta < \omega^2}(\beta-\Pi^1_1)$ and Δ(ω2-Π11). We also define 01♯ as 0♯ and in general, 0(k + 1)♯ as (0k♯)♯. We then show that the existence of 0(k + 1)♯ is equivalent to the determinacy of ((k + 1) * Σ01)* as well as the determinacy of (k * Σ01)*+. |
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ISSN: | 0022-4812 1943-5886 |
DOI: | 10.2307/2274643 |