I[omega₂] can be the nonstationary ideal on Cof(omega₁)

2004/07/13 by Mitchell, William J.
#03E35 #FOS: Mathematics #Logic (math.LO)

paper · doi:10.48550/arxiv.math/0407225

Abstract

We answer a question of Shelah by showing that it is consistent that every set of ordinals of cofinality omega₁ in I[omega₂] is nonstationary if and only if it is consistent that that there is a kappa⁺ Mahlo cardinal kappa.

Related

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• Cofinality of normal ideals on P_κ(λ), I
• Towers and clubs
• Forcing Axioms and the Definabilty of the Nonstationary Ideal on ω₁
• Ideals, Cohen sets and consistent extensions of the Erdős-Dushnik-Miller Theorem