Cofinal types on ω2

IF 0.4 4区数学 Q4 LOGIC

Mathematical Logic Quarterly Pub Date : 2023-05-31 DOI:10.1002/malq.202200021

Borisa Kuzeljevic, Stevo Todorcevic

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引用次数: 3

Abstract

In this paper we start the analysis of the class $D_{ℵ_{2}}$ , the class of cofinal types of directed sets of cofinality at most ℵ₂. We compare elements of $D_{ℵ_{2}}$ using the notion of Tukey reducibility. We isolate some simple cofinal types in $D_{ℵ_{2}}$ , and then proceed to find some of these types which have an immediate successor in the Tukey ordering of $D_{ℵ_{2}}$ .

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ω2上的共尾型

在本文中，我们开始分析D类ℵ 2$\mathcal{D}_｛\aleph_2｝$，至多有向共尾集的一类共尾类型ℵ2.我们比较D的元素ℵ 2$\mathcal{D}_｛\aleph_2｝$使用Tukey可约性的概念。我们在D中分离出一些简单的共尾类型ℵ 2$\mathcal{D}_｛\aleph_2｝$，然后继续寻找其中一些在D的Tukey排序中具有直接后继的类型ℵ 2$\mathcal{D}_｛\alph_2｝$。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Mathematical Logic Quarterly 数学-数学

CiteScore

0.60

自引率

0.00%

发文量

审稿时长

>12 weeks

期刊介绍： Mathematical Logic Quarterly publishes original contributions on mathematical logic and foundations of mathematics and related areas, such as general logic, model theory, recursion theory, set theory, proof theory and constructive mathematics, algebraic logic, nonstandard models, and logical aspects of theoretical computer science.