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arXiv · 2107.09339

Usuba's principle $UB_\lambda$ can fail at singular cardinals

Mohammad Golshani·Saharon Shelah
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Abstract

We answer a question of Usuba by showing that the combinatorial principle $UB_\lambda$ can fail at a singular cardinal. Furthermore, $\lambda$ can be taken to be $\aleph_\omega.$

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Mohammad Golshani, Saharon Shelah. 2021-07-20. Usuba's principle $UB_\lambda$ can fail at singular cardinals. https://arxiv.org/abs/2107.09339

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