{"title":"Pcf 无选择 Sh835","authors":"Saharon Shelah","doi":"10.1007/s00153-023-00900-7","DOIUrl":null,"url":null,"abstract":"<div><p>We mainly investigate models of set theory with restricted choice, e.g., ZF + DC + the family of countable subsets of <span>\\(\\lambda \\)</span> is well ordered for every <span>\\(\\lambda \\)</span> (really local version for a given <span>\\(\\lambda \\)</span>). We think that in this frame much of pcf theory, (and combinatorial set theory in general) can be generalized. We prove here, in particular, that there is a proper class of regular cardinals, every large enough successor of singular is not measurable and we can prove cardinal inequalities. Solving some open problems, we prove that if <span>\\(\\mu> \\kappa = \\textrm{cf}(\\mu ) > \\aleph _{0},\\)</span> then from a well ordering of <span>\\({\\mathscr {P}}({\\mathscr {P}}(\\kappa )) \\cup {}^{\\kappa >} \\mu \\)</span> we can define a well ordering of <span>\\({}^{\\kappa } \\mu .\\)</span></p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"63 5-6","pages":"623 - 654"},"PeriodicalIF":0.3000,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Pcf without choice Sh835\",\"authors\":\"Saharon Shelah\",\"doi\":\"10.1007/s00153-023-00900-7\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>We mainly investigate models of set theory with restricted choice, e.g., ZF + DC + the family of countable subsets of <span>\\\\(\\\\lambda \\\\)</span> is well ordered for every <span>\\\\(\\\\lambda \\\\)</span> (really local version for a given <span>\\\\(\\\\lambda \\\\)</span>). We think that in this frame much of pcf theory, (and combinatorial set theory in general) can be generalized. We prove here, in particular, that there is a proper class of regular cardinals, every large enough successor of singular is not measurable and we can prove cardinal inequalities. Solving some open problems, we prove that if <span>\\\\(\\\\mu> \\\\kappa = \\\\textrm{cf}(\\\\mu ) > \\\\aleph _{0},\\\\)</span> then from a well ordering of <span>\\\\({\\\\mathscr {P}}({\\\\mathscr {P}}(\\\\kappa )) \\\\cup {}^{\\\\kappa >} \\\\mu \\\\)</span> we can define a well ordering of <span>\\\\({}^{\\\\kappa } \\\\mu .\\\\)</span></p></div>\",\"PeriodicalId\":48853,\"journal\":{\"name\":\"Archive for Mathematical Logic\",\"volume\":\"63 5-6\",\"pages\":\"623 - 654\"},\"PeriodicalIF\":0.3000,\"publicationDate\":\"2024-03-22\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Archive for Mathematical Logic\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://link.springer.com/article/10.1007/s00153-023-00900-7\",\"RegionNum\":4,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"Arts and Humanities\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Archive for Mathematical Logic","FirstCategoryId":"100","ListUrlMain":"https://link.springer.com/article/10.1007/s00153-023-00900-7","RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"Arts and Humanities","Score":null,"Total":0}
We mainly investigate models of set theory with restricted choice, e.g., ZF + DC + the family of countable subsets of \(\lambda \) is well ordered for every \(\lambda \) (really local version for a given \(\lambda \)). We think that in this frame much of pcf theory, (and combinatorial set theory in general) can be generalized. We prove here, in particular, that there is a proper class of regular cardinals, every large enough successor of singular is not measurable and we can prove cardinal inequalities. Solving some open problems, we prove that if \(\mu> \kappa = \textrm{cf}(\mu ) > \aleph _{0},\) then from a well ordering of \({\mathscr {P}}({\mathscr {P}}(\kappa )) \cup {}^{\kappa >} \mu \) we can define a well ordering of \({}^{\kappa } \mu .\)
期刊介绍:
The journal publishes research papers and occasionally surveys or expositions on mathematical logic. Contributions are also welcomed from other related areas, such as theoretical computer science or philosophy, as long as the methods of mathematical logic play a significant role. The journal therefore addresses logicians and mathematicians, computer scientists, and philosophers who are interested in the applications of mathematical logic in their own field, as well as its interactions with other areas of research.