{"title":"后继基数的紧凑性与巨大性","authors":"Sean D. Cox, Monroe Eskew","doi":"10.1142/s0219061322500167","DOIUrl":null,"url":null,"abstract":"If $\\kappa$ is regular and $2^{<\\kappa}\\leq\\kappa^+$, then the existence of a weakly presaturated ideal on $\\kappa^+$ implies $\\square^*_\\kappa$. This partially answers a question of Foreman and Magidor about the approachability ideal on $\\omega_2$. As a corollary, we show that if there is a presaturated ideal $I$ on $\\omega_2$ such that $\\mathcal{P}(\\omega_2)/I$ is semiproper, then CH holds. We also show some barriers to getting the tree property and a saturated ideal simultaneously on a successor cardinal from conventional forcing methods.","PeriodicalId":50144,"journal":{"name":"Journal of Mathematical Logic","volume":"646 1","pages":"2250016:1-2250016:16"},"PeriodicalIF":0.9000,"publicationDate":"2020-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":"{\"title\":\"Compactness versus hugeness at successor cardinals\",\"authors\":\"Sean D. Cox, Monroe Eskew\",\"doi\":\"10.1142/s0219061322500167\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"If $\\\\kappa$ is regular and $2^{<\\\\kappa}\\\\leq\\\\kappa^+$, then the existence of a weakly presaturated ideal on $\\\\kappa^+$ implies $\\\\square^*_\\\\kappa$. This partially answers a question of Foreman and Magidor about the approachability ideal on $\\\\omega_2$. As a corollary, we show that if there is a presaturated ideal $I$ on $\\\\omega_2$ such that $\\\\mathcal{P}(\\\\omega_2)/I$ is semiproper, then CH holds. We also show some barriers to getting the tree property and a saturated ideal simultaneously on a successor cardinal from conventional forcing methods.\",\"PeriodicalId\":50144,\"journal\":{\"name\":\"Journal of Mathematical Logic\",\"volume\":\"646 1\",\"pages\":\"2250016:1-2250016:16\"},\"PeriodicalIF\":0.9000,\"publicationDate\":\"2020-09-29\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"1\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Mathematical Logic\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://doi.org/10.1142/s0219061322500167\",\"RegionNum\":1,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"LOGIC\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Mathematical Logic","FirstCategoryId":"100","ListUrlMain":"https://doi.org/10.1142/s0219061322500167","RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"LOGIC","Score":null,"Total":0}
Compactness versus hugeness at successor cardinals
If $\kappa$ is regular and $2^{<\kappa}\leq\kappa^+$, then the existence of a weakly presaturated ideal on $\kappa^+$ implies $\square^*_\kappa$. This partially answers a question of Foreman and Magidor about the approachability ideal on $\omega_2$. As a corollary, we show that if there is a presaturated ideal $I$ on $\omega_2$ such that $\mathcal{P}(\omega_2)/I$ is semiproper, then CH holds. We also show some barriers to getting the tree property and a saturated ideal simultaneously on a successor cardinal from conventional forcing methods.
期刊介绍:
The Journal of Mathematical Logic (JML) provides an important forum for the communication of original contributions in all areas of mathematical logic and its applications. It aims at publishing papers at the highest level of mathematical creativity and sophistication. JML intends to represent the most important and innovative developments in the subject.