{"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":0,"journal":{"name":"","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"","FirstCategoryId":"100","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/malq.202100020","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","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 .