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arXiv 2401.15693math.LO
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平方序列、超滤子与力迫公理

Squares, ultrafilters and forcing axioms

Chris Lambie-Hanson, Assaf Rinot, Jing Zhang

AI总结:

该研究探讨集合论中平方序列、超滤子与力迫公理的关联,证明强力迫公理可与弱带索引平方序列相容、带索引平方序列可与合适参数的不可分解超滤子共存,且正常力迫公理下承载一致不可分解超滤子的基数性质结论最优,推进了集合论紧致性原理的研究。

摘要:

我们研究了各类集合论紧致性原理之间的关联,重点关注标题中提及的三类组合对象或原理之间的相互作用。具体而言,我们证明了以下结论:(1) 通常与带索引平方序列的存在性不相容的强力迫公理,可被构造为与带索引平方序列的较弱版本相容。(2) 带索引平方序列与参数合适的不可分解超滤子可以共存。由此可得,由一致不可分解超滤子的存在性所蕴涵的平稳反射程度是最优的。(3) 正常力迫公理(Proper Forcing Axiom)蕴涵,任何承载一致不可分解超滤子的基数要么是可测基数,要么是可数个可测基数的上确界。借助前文的结论,我们证明该结论无法被改进。

英文摘要:

We study relationships between various set theoretic compactness principles, focusing on the interplay between the three families of combinatorial objects or principles mentioned in the title. Specifically, we show the following. (1) Strong forcing axioms, in general incompatible with the existence of indexed squares, can be made compatible with weaker versions of indexed squares. (2) Indexed squares and indecomposable ultrafilters with suitable parameters can coexist. As a consequence, the amount of stationary reflection known to be implied by the existence of a uniform indecomposable ultrafilter is optimal. (3) The Proper Forcing Axiom implies that any cardinal carrying a uniform indecomposable ultrafilter is either measurable or a supremum of countably many measurable cardinals. Leveraging insights from the preceding sections, we demonstrate that the conclusion cannot be improved.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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