{"title":"关于绝对 $$\\kappa$ -Borel 集在紧凑集上的凝聚的第一个巴拿赫问题","authors":"A. V. Osipov","doi":"10.1007/s10474-024-01428-9","DOIUrl":null,"url":null,"abstract":"<div><p>It is consistent that the continuum be arbitrary large and no absolute <span>\\(\\kappa\\)</span>-Borel set X of density <span>\\(\\kappa\\)</span>, <span>\\(\\aleph_1<\\kappa<\\mathfrak{c}\\)</span>,condenses onto a compactum.</p><p>It is consistent that the continuum be arbitrary large and any absolute <span>\\(\\kappa\\)</span>-Borel set X of density <span>\\(\\kappa\\)</span>, <span>\\(\\kappa\\leq\\mathfrak{c}\\)</span>, containing a closed subspace of the Baire space of weight <span>\\(\\kappa\\)</span>, condenses onto a compactum.</p><p>In particular, applying Brian's results in model theory, we get the following unexpected result. Given any <span>\\(A\\subseteq \\mathbb{N}\\)</span> with <span>\\(1\\in A\\)</span>, there is a forcing extension in which every absolute <span>\\(\\aleph_n\\)</span>-Borel set, containing a closed subspace of the Baire space of weight <span>\\(\\aleph_n\\)</span>, condenses onto a compactum if and only if <span>\\(n\\in A\\)</span>.</p></div>","PeriodicalId":50894,"journal":{"name":"Acta Mathematica Hungarica","volume":"173 1","pages":"169 - 175"},"PeriodicalIF":0.6000,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"On the first Banach problem concerning condensations of absolute \\\\(\\\\kappa\\\\)-Borel sets onto compacta\",\"authors\":\"A. V. Osipov\",\"doi\":\"10.1007/s10474-024-01428-9\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>It is consistent that the continuum be arbitrary large and no absolute <span>\\\\(\\\\kappa\\\\)</span>-Borel set X of density <span>\\\\(\\\\kappa\\\\)</span>, <span>\\\\(\\\\aleph_1<\\\\kappa<\\\\mathfrak{c}\\\\)</span>,condenses onto a compactum.</p><p>It is consistent that the continuum be arbitrary large and any absolute <span>\\\\(\\\\kappa\\\\)</span>-Borel set X of density <span>\\\\(\\\\kappa\\\\)</span>, <span>\\\\(\\\\kappa\\\\leq\\\\mathfrak{c}\\\\)</span>, containing a closed subspace of the Baire space of weight <span>\\\\(\\\\kappa\\\\)</span>, condenses onto a compactum.</p><p>In particular, applying Brian's results in model theory, we get the following unexpected result. Given any <span>\\\\(A\\\\subseteq \\\\mathbb{N}\\\\)</span> with <span>\\\\(1\\\\in A\\\\)</span>, there is a forcing extension in which every absolute <span>\\\\(\\\\aleph_n\\\\)</span>-Borel set, containing a closed subspace of the Baire space of weight <span>\\\\(\\\\aleph_n\\\\)</span>, condenses onto a compactum if and only if <span>\\\\(n\\\\in A\\\\)</span>.</p></div>\",\"PeriodicalId\":50894,\"journal\":{\"name\":\"Acta Mathematica Hungarica\",\"volume\":\"173 1\",\"pages\":\"169 - 175\"},\"PeriodicalIF\":0.6000,\"publicationDate\":\"2024-05-06\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Acta Mathematica Hungarica\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://link.springer.com/article/10.1007/s10474-024-01428-9\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Mathematica Hungarica","FirstCategoryId":"100","ListUrlMain":"https://link.springer.com/article/10.1007/s10474-024-01428-9","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
On the first Banach problem concerning condensations of absolute \(\kappa\)-Borel sets onto compacta
It is consistent that the continuum be arbitrary large and no absolute \(\kappa\)-Borel set X of density \(\kappa\), \(\aleph_1<\kappa<\mathfrak{c}\),condenses onto a compactum.
It is consistent that the continuum be arbitrary large and any absolute \(\kappa\)-Borel set X of density \(\kappa\), \(\kappa\leq\mathfrak{c}\), containing a closed subspace of the Baire space of weight \(\kappa\), condenses onto a compactum.
In particular, applying Brian's results in model theory, we get the following unexpected result. Given any \(A\subseteq \mathbb{N}\) with \(1\in A\), there is a forcing extension in which every absolute \(\aleph_n\)-Borel set, containing a closed subspace of the Baire space of weight \(\aleph_n\), condenses onto a compactum if and only if \(n\in A\).
期刊介绍:
Acta Mathematica Hungarica is devoted to publishing research articles of top quality in all areas of pure and applied mathematics as well as in theoretical computer science. The journal is published yearly in three volumes (two issues per volume, in total 6 issues) in both print and electronic formats. Acta Mathematica Hungarica (formerly Acta Mathematica Academiae Scientiarum Hungaricae) was founded in 1950 by the Hungarian Academy of Sciences.