无无限反链的偏序集的链覆盖数

IF 0.8 4区 数学 Q2 MATHEMATICS Comptes Rendus Mathematique Pub Date : 2023-10-31 DOI:10.5802/crmath.511
Uri Abraham, Maurice Pouzet
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引用次数: 0

摘要

对于不可数基数ν,我们给出一个具有基数和覆盖数ν的序集列表,使得对于每一个不存在无限反链的序集P, Cov(P)≥ν当且仅当P嵌入该列表中的一个元素。如果ν是后继基数,即[ν] 2及其对偶,则该列表有两个元素;如果ν是cf(ν)弱紧的极限基数,则该列表有四个元素。对于ν=¹,第一作者给出了一个列表;他的构造被F. Dorais推广到每一个无限的后继的基本空间。
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The chain covering number of a poset with no infinite antichains
The chain covering number Cov(P) of a poset P is the least number of chains needed to cover P. For an uncountable cardinal ν, we give a list of posets of cardinality and covering number ν such that for every poset P with no infinite antichain, Cov(P)≥ν if and only if P embeds a member of the list. This list has two elements if ν is a successor cardinal, namely [ν] 2 and its dual, and four elements if ν is a limit cardinal with cf(ν) weakly compact. For ν=ℵ 1 , a list was given by the first author; his construction was extended by F. Dorais to every infinite successor cardinal ν.
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来源期刊
CiteScore
1.30
自引率
0.00%
发文量
115
审稿时长
16.6 weeks
期刊介绍: The Comptes Rendus - Mathématique cover all fields of the discipline: Logic, Combinatorics, Number Theory, Group Theory, Mathematical Analysis, (Partial) Differential Equations, Geometry, Topology, Dynamical systems, Mathematical Physics, Mathematical Problems in Mechanics, Signal Theory, Mathematical Economics, … Articles are original notes that briefly describe an important discovery or result. The articles are written in French or English. The journal also publishes review papers, thematic issues and texts reflecting the activity of Académie des sciences in the field of Mathematics.
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