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arXiv · 1804.10383

Games and Ramsey-like cardinals

Dan Saattrup Nielsen·Philip Welch
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Abstract

We generalise the $α$-Ramsey cardinals introduced in Holy and Schlicht (2018) for cardinals $α$ to arbitrary ordinals $α$, and answer several questions posed in that paper. In particular, we show that $α$-Ramseys are downwards absolute to the core model $K$ for all $α$ of uncountable cofinality, that strategic $ω$-Ramsey cardinals are equiconsistent with remarkable cardinals and that strategic $α$-Ramsey cardinals are equiconsistent with measurable cardinals for all $α>ω$. We also show that the $n$-Ramseys satisfy indescribability properties and use them to provide a game-theoretic characterisation of completely ineffable cardinals, as well as establishing further connections between the $α$-Ramsey cardinals and the Ramsey-like cardinals introduced in Gitman (2011), Feng (1990) and Sharpe and Welch (2011).

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Dan Saattrup Nielsen, Philip Welch. 2018-10-30. Games and Ramsey-like cardinals. https://arxiv.org/abs/1804.10383

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