{"title":"更小的非σ -分散线性阶数。","authors":"Roy Shalev","doi":"10.1007/s40879-024-00780-y","DOIUrl":null,"url":null,"abstract":"<p><p>In a recent paper, Cummings, Eisworth and Moore gave a novel construction of minimal non- <math><mi>σ</mi></math> -scattered linear orders of arbitrarily large successor size. It remained open whether it is possible to construct these orders at other cardinals. Here, it is proved that in Gödel's constructible universe, these orders exist at any regular uncountable cardinal <math><mi>κ</mi></math> that is not weakly compact. In fact, for any cardinal <math><mi>κ</mi></math> as above we obtain <math><msup><mn>2</mn> <mi>κ</mi></msup> </math> many such orders which are pairwise non-embeddable. At the level of <math><msub><mi>ℵ</mi> <mn>1</mn></msub> </math> , their work answered an old question of Baumgartner by constructing from <math><mo>♢</mo></math> a minimal Aronszajn line that is not Souslin. Our uniform construction is based on the Brodsky-Rinot proxy principle which at the level of <math><msub><mi>ℵ</mi> <mn>1</mn></msub> </math> is strictly weaker than <math><mo>♢</mo></math> .</p>","PeriodicalId":44725,"journal":{"name":"European Journal of Mathematics","volume":"10 4","pages":"74"},"PeriodicalIF":0.5000,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11611987/pdf/","citationCount":"0","resultStr":"{\"title\":\"<ArticleTitle xmlns:ns0=\\\"http://www.w3.org/1998/Math/MathML\\\">More minimal non- <ns0:math><ns0:mi>σ</ns0:mi></ns0:math> -scattered linear orders.\",\"authors\":\"Roy Shalev\",\"doi\":\"10.1007/s40879-024-00780-y\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>In a recent paper, Cummings, Eisworth and Moore gave a novel construction of minimal non- <math><mi>σ</mi></math> -scattered linear orders of arbitrarily large successor size. It remained open whether it is possible to construct these orders at other cardinals. Here, it is proved that in Gödel's constructible universe, these orders exist at any regular uncountable cardinal <math><mi>κ</mi></math> that is not weakly compact. In fact, for any cardinal <math><mi>κ</mi></math> as above we obtain <math><msup><mn>2</mn> <mi>κ</mi></msup> </math> many such orders which are pairwise non-embeddable. At the level of <math><msub><mi>ℵ</mi> <mn>1</mn></msub> </math> , their work answered an old question of Baumgartner by constructing from <math><mo>♢</mo></math> a minimal Aronszajn line that is not Souslin. Our uniform construction is based on the Brodsky-Rinot proxy principle which at the level of <math><msub><mi>ℵ</mi> <mn>1</mn></msub> </math> is strictly weaker than <math><mo>♢</mo></math> .</p>\",\"PeriodicalId\":44725,\"journal\":{\"name\":\"European Journal of Mathematics\",\"volume\":\"10 4\",\"pages\":\"74\"},\"PeriodicalIF\":0.5000,\"publicationDate\":\"2024-01-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11611987/pdf/\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"European Journal of Mathematics\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1007/s40879-024-00780-y\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"2024/12/2 0:00:00\",\"PubModel\":\"Epub\",\"JCR\":\"Q3\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"European Journal of Mathematics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1007/s40879-024-00780-y","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/12/2 0:00:00","PubModel":"Epub","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
In a recent paper, Cummings, Eisworth and Moore gave a novel construction of minimal non- -scattered linear orders of arbitrarily large successor size. It remained open whether it is possible to construct these orders at other cardinals. Here, it is proved that in Gödel's constructible universe, these orders exist at any regular uncountable cardinal that is not weakly compact. In fact, for any cardinal as above we obtain many such orders which are pairwise non-embeddable. At the level of , their work answered an old question of Baumgartner by constructing from a minimal Aronszajn line that is not Souslin. Our uniform construction is based on the Brodsky-Rinot proxy principle which at the level of is strictly weaker than .
期刊介绍:
The European Journal of Mathematics (EJM) is an international journal that publishes research papers in all fields of mathematics. It also publishes research-survey papers intended to provide nonspecialists with insight into topics of current research in different areas of mathematics. The journal invites authors from all over the world. All contributions are required to meet high standards of quality and originality. EJM has an international editorial board. Coverage in EJM will include: - Algebra - Complex Analysis - Differential Equations - Discrete Mathematics - Functional Analysis - Geometry and Topology - Mathematical Logic and Foundations - Number Theory - Numerical Analysis and Optimization - Probability and Statistics - Real Analysis.