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arXiv · 1810.12542

On Harrington's model in which Separation holds but Reduction fails at the 3rd projective level, and on some related models of Sami

Vladimir Kanovei·Vassily Lyubetsky
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Abstract

In a handwtitten note of 1975, Leo Harrington sketched a construction of a model of ZFC (no large cardinals or anything beyond ZFC!) in which $\mathbfΠ^1_3$-Separation holds but $\mathbfΣ^1_3$-Reduction fails. The result has never appeared in a journal or book publication except for a few of old references.

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Vladimir Kanovei, Vassily Lyubetsky. 2018-11-11. On Harrington's model in which Separation holds but Reduction fails at the 3rd projective level, and on some related models of Sami. https://arxiv.org/abs/1810.12542

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