论文标题

等效关系的新跳跃操作员

New jump operators on equivalence relations

论文作者

Clemens, John D., Coskey, Samuel

论文摘要

我们介绍了一个关于鲍尔等效关系的新型跳跃操作员家族。具体来说,对于每个可数组$γ$,我们引入了$γ$ - 跳跃。我们研究$γ$ - 跳跃的基本特性,并将它们与其他先前研究的跳跃操作员进行比较。我们的主要结果之一是确定,对于许多$γ$,$γ$ - jump是\ emph {promer}的意义,因为对于任何borel等价关系$ e $ $ $γ$ - $ e $ $ e $的$ gump均严格高于Borel降低性的nierArchy的$ e $。另一方面,有$γ$的组$γ$不合适的例子。为了建立合适性,我们对自动形态群体的连续行动引起的鲍尔等效关系的分析是我们表示的整个$γ$ -tree,并将其与$γ$ - 浓度的迭代相关联。我们还产生了几个新的等效关系示例,这些示例是将$γ$ - 跳跃物应用于经典研究的等价关系并得出与这些关系相关的通用性奇迹性结果。我们应用结果表明,可计数散射线性订单的同构问题的复杂性随着等级而正确增加。

We introduce a new family of jump operators on Borel equivalence relations; specifically, for each countable group $Γ$ we introduce the $Γ$-jump. We study the elementary properties of the $Γ$-jumps and compare them with other previously studied jump operators. One of our main results is to establish that for many groups $Γ$, the $Γ$-jump is \emph{proper} in the sense that for any Borel equivalence relation $E$ the $Γ$-jump of $E$ is strictly higher than $E$ in the Borel reducibility hierarchy. On the other hand there are examples of groups $Γ$ for which the $Γ$-jump is not proper. To establish properness, we produce an analysis of Borel equivalence relations induced by continuous actions of the automorphism group of what we denote the full $Γ$-tree, and relate these to iterates of the $Γ$-jump. We also produce several new examples of equivalence relations that arise from applying the $Γ$-jump to classically studied equivalence relations and derive generic ergodicity results related to these. We apply our results to show that the complexity of the isomorphism problem for countable scattered linear orders properly increases with the rank.

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