{"title":"The theory of hereditarily bounded sets","authors":"Emil Jeřábek","doi":"10.1002/malq.202100020","DOIUrl":null,"url":null,"abstract":"<p>We show that for any <math>\n <semantics>\n <mrow>\n <mi>k</mi>\n <mo>∈</mo>\n <mi>ω</mi>\n </mrow>\n <annotation>$k\\in \\omega$</annotation>\n </semantics></math>, the structure <math>\n <semantics>\n <mrow>\n <mo>⟨</mo>\n <msub>\n <mi>H</mi>\n <mi>k</mi>\n </msub>\n <mo>,</mo>\n <mo>∈</mo>\n <mo>⟩</mo>\n </mrow>\n <annotation>$\\langle H_k,{\\in }\\rangle$</annotation>\n </semantics></math> of sets that are hereditarily of size at most <i>k</i> is decidable. We provide a transparent complete axiomatization of its theory, a quantifier elimination result, and tight bounds on its computational complexity. This stands in stark contrast to the structure <math>\n <semantics>\n <mrow>\n <msub>\n <mi>V</mi>\n <mi>ω</mi>\n </msub>\n <mo>=</mo>\n <msub>\n <mo>⋃</mo>\n <mi>k</mi>\n </msub>\n <msub>\n <mi>H</mi>\n <mi>k</mi>\n </msub>\n </mrow>\n <annotation>$V_\\omega =\\bigcup _kH_k$</annotation>\n </semantics></math> of hereditarily finite sets, which is well known to be bi-interpretable with the standard model of arithmetic <math>\n <semantics>\n <mrow>\n <mo>⟨</mo>\n <mi>N</mi>\n <mo>,</mo>\n <mo>+</mo>\n <mo>,</mo>\n <mo>·</mo>\n <mo>⟩</mo>\n </mrow>\n <annotation>$\\langle \\mathbb {N},+,\\cdot \\rangle$</annotation>\n </semantics></math>.</p>","PeriodicalId":49864,"journal":{"name":"Mathematical Logic Quarterly","volume":"68 2","pages":"243-256"},"PeriodicalIF":0.4000,"publicationDate":"2022-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Mathematical Logic Quarterly","FirstCategoryId":"100","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/malq.202100020","RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"LOGIC","Score":null,"Total":0}
引用次数: 1
Abstract
We show that for any , the structure of sets that are hereditarily of size at most k is decidable. We provide a transparent complete axiomatization of its theory, a quantifier elimination result, and tight bounds on its computational complexity. This stands in stark contrast to the structure of hereditarily finite sets, which is well known to be bi-interpretable with the standard model of arithmetic .
期刊介绍:
Mathematical Logic Quarterly publishes original contributions on mathematical logic and foundations of mathematics and related areas, such as general logic, model theory, recursion theory, set theory, proof theory and constructive mathematics, algebraic logic, nonstandard models, and logical aspects of theoretical computer science.