{"title":"围绕 p-adically 闭域中的可定义类型","authors":"Pablo Andújar Guerrero , Will Johnson","doi":"10.1016/j.apal.2024.103484","DOIUrl":null,"url":null,"abstract":"<div><p>We prove some technical results on definable types in <em>p</em>-adically closed fields, with consequences for definable groups and definable topological spaces. First, the code of a definable <em>n</em>-type (in the field sort) can be taken to be a real tuple (in the field sort) rather than an imaginary tuple (in the geometric sorts). Second, any definable type in the real or imaginary sorts is generated by a countable union of chains parameterized by the value group. Third, if <em>X</em> is an interpretable set, then the space of global definable types on <em>X</em> is strictly pro-interpretable, building off work of Cubides Kovacsics, Hils, and Ye <span>[7]</span>, <span>[8]</span>. Fourth, global definable types can be lifted (in a non-canonical way) along interpretable surjections. Fifth, if <em>G</em> is a definable group with definable f-generics (<em>dfg</em>), and <em>G</em> acts on a definable set <em>X</em>, then the quotient space <span><math><mi>X</mi><mo>/</mo><mi>G</mi></math></span> is definable, not just interpretable. This explains some phenomena observed by Pillay and Yao <span>[24]</span>. Lastly, we show that interpretable topological spaces satisfy analogues of first-countability and curve selection. Using this, we show that all reasonable notions of definable compactness agree on interpretable topological spaces, and that definable compactness is definable in families.</p></div>","PeriodicalId":50762,"journal":{"name":"Annals of Pure and Applied Logic","volume":"175 10","pages":"Article 103484"},"PeriodicalIF":0.6000,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Around definable types in p-adically closed fields\",\"authors\":\"Pablo Andújar Guerrero , Will Johnson\",\"doi\":\"10.1016/j.apal.2024.103484\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>We prove some technical results on definable types in <em>p</em>-adically closed fields, with consequences for definable groups and definable topological spaces. First, the code of a definable <em>n</em>-type (in the field sort) can be taken to be a real tuple (in the field sort) rather than an imaginary tuple (in the geometric sorts). Second, any definable type in the real or imaginary sorts is generated by a countable union of chains parameterized by the value group. Third, if <em>X</em> is an interpretable set, then the space of global definable types on <em>X</em> is strictly pro-interpretable, building off work of Cubides Kovacsics, Hils, and Ye <span>[7]</span>, <span>[8]</span>. Fourth, global definable types can be lifted (in a non-canonical way) along interpretable surjections. Fifth, if <em>G</em> is a definable group with definable f-generics (<em>dfg</em>), and <em>G</em> acts on a definable set <em>X</em>, then the quotient space <span><math><mi>X</mi><mo>/</mo><mi>G</mi></math></span> is definable, not just interpretable. This explains some phenomena observed by Pillay and Yao <span>[24]</span>. Lastly, we show that interpretable topological spaces satisfy analogues of first-countability and curve selection. Using this, we show that all reasonable notions of definable compactness agree on interpretable topological spaces, and that definable compactness is definable in families.</p></div>\",\"PeriodicalId\":50762,\"journal\":{\"name\":\"Annals of Pure and Applied Logic\",\"volume\":\"175 10\",\"pages\":\"Article 103484\"},\"PeriodicalIF\":0.6000,\"publicationDate\":\"2024-06-04\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Annals of Pure and Applied Logic\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0168007224000885\",\"RegionNum\":2,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"LOGIC\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Annals of Pure and Applied Logic","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0168007224000885","RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"LOGIC","Score":null,"Total":0}
引用次数: 0
摘要
我们证明了 p-adically closed fields 中可定义类型的一些技术结果,这些结果对可定义群和可定义拓扑空间都有影响。首先,可定义 n 型的代码(在字段排序中)可以被视为实元组(在字段排序中),而不是虚元组(在几何排序中)。其次,在实排序或虚排序中,任何可定义类型都是由值组参数化的链的可数联盟生成的。第三,如果 X 是一个可解释集合,那么 X 上的全局可定义类型空间严格来说是亲可解释的,这是建立在 Cubides Kovacsics、Hils 和 Ye [7], [8] 的工作基础之上的。第四,全局可定义类型可以(以非规范的方式)沿着可解释的投射提升。第五,如果 G 是具有可定义 f 元(dfg)的可定义群,并且 G 作用于可定义集合 X,那么商空间 X/G 是可定义的,而不仅仅是可解释的。这解释了 Pillay 和 Yao [24] 观察到的一些现象。最后,我们证明可解释拓扑空间满足第一可数性和曲线选择的类似条件。由此,我们证明了可定义紧凑性的所有合理概念都与可解释拓扑空间一致,而且可定义紧凑性在族中是可定义的。
Around definable types in p-adically closed fields
We prove some technical results on definable types in p-adically closed fields, with consequences for definable groups and definable topological spaces. First, the code of a definable n-type (in the field sort) can be taken to be a real tuple (in the field sort) rather than an imaginary tuple (in the geometric sorts). Second, any definable type in the real or imaginary sorts is generated by a countable union of chains parameterized by the value group. Third, if X is an interpretable set, then the space of global definable types on X is strictly pro-interpretable, building off work of Cubides Kovacsics, Hils, and Ye [7], [8]. Fourth, global definable types can be lifted (in a non-canonical way) along interpretable surjections. Fifth, if G is a definable group with definable f-generics (dfg), and G acts on a definable set X, then the quotient space is definable, not just interpretable. This explains some phenomena observed by Pillay and Yao [24]. Lastly, we show that interpretable topological spaces satisfy analogues of first-countability and curve selection. Using this, we show that all reasonable notions of definable compactness agree on interpretable topological spaces, and that definable compactness is definable in families.
期刊介绍:
The journal Annals of Pure and Applied Logic publishes high quality papers in all areas of mathematical logic as well as applications of logic in mathematics, in theoretical computer science and in other related disciplines. All submissions to the journal should be mathematically correct, well written (preferably in English)and contain relevant new results that are of significant interest to a substantial number of logicians. The journal also considers submissions that are somewhat too long to be published by other journals while being too short to form a separate memoir provided that they are of particular outstanding quality and broad interest. In addition, Annals of Pure and Applied Logic occasionally publishes special issues of selected papers from well-chosen conferences in pure and applied logic.