{"title":"Limit models in strictly stable abstract elementary classes","authors":"Will Boney, Monica M. VanDieren","doi":"10.1002/malq.202200075","DOIUrl":null,"url":null,"abstract":"<p>In this paper, we examine the locality condition for non-splitting and determine the level of uniqueness of limit models that can be recovered in some stable, but not superstable, abstract elementary classes. In particular we prove the following. Suppose that <span></span><math>\n <semantics>\n <mi>K</mi>\n <annotation>$\\mathcal {K}$</annotation>\n </semantics></math> is an abstract elementary class satisfying\n\n </p><p>Then for <span></span><math>\n <semantics>\n <mi>ϑ</mi>\n <annotation>$\\vartheta$</annotation>\n </semantics></math> and <span></span><math>\n <semantics>\n <mi>δ</mi>\n <annotation>$\\delta$</annotation>\n </semantics></math> limit ordinals <span></span><math>\n <semantics>\n <mrow>\n <mo><</mo>\n <msup>\n <mi>μ</mi>\n <mo>+</mo>\n </msup>\n </mrow>\n <annotation>$<\\mu ^+$</annotation>\n </semantics></math> both with cofinality <span></span><math>\n <semantics>\n <mrow>\n <mo>≥</mo>\n <msubsup>\n <mi>κ</mi>\n <mi>μ</mi>\n <mo>∗</mo>\n </msubsup>\n <mrow>\n <mo>(</mo>\n <mi>K</mi>\n <mo>)</mo>\n </mrow>\n </mrow>\n <annotation>$\\ge \\kappa ^*_\\mu (\\mathcal {K})$</annotation>\n </semantics></math>, if <span></span><math>\n <semantics>\n <mi>K</mi>\n <annotation>$\\mathcal {K}$</annotation>\n </semantics></math> satisfies symmetry for <span></span><math>\n <semantics>\n <mrow>\n <mi>non</mi>\n <mi>-</mi>\n <mi>μ</mi>\n <mi>-</mi>\n <mi>splitting</mi>\n </mrow>\n <annotation>${\\rm non}\\text{-}\\mu\\text{-}{\\rm splitting}$</annotation>\n </semantics></math> (or just <span></span><math>\n <semantics>\n <mrow>\n <mo>(</mo>\n <mi>μ</mi>\n <mo>,</mo>\n <mi>δ</mi>\n <mo>)</mo>\n </mrow>\n <annotation>$(\\mu,\\delta)$</annotation>\n </semantics></math>-symmetry), then, for any <span></span><math>\n <semantics>\n <msub>\n <mi>M</mi>\n <mn>1</mn>\n </msub>\n <annotation>$M_1$</annotation>\n </semantics></math> and <span></span><math>\n <semantics>\n <msub>\n <mi>M</mi>\n <mn>2</mn>\n </msub>\n <annotation>$M_2$</annotation>\n </semantics></math> that are <span></span><math>\n <semantics>\n <mrow>\n <mo>(</mo>\n <mi>μ</mi>\n <mo>,</mo>\n <mi>ϑ</mi>\n <mo>)</mo>\n </mrow>\n <annotation>$(\\mu,\\vartheta)$</annotation>\n </semantics></math> and <span></span><math>\n <semantics>\n <mrow>\n <mo>(</mo>\n <mi>μ</mi>\n <mo>,</mo>\n <mi>δ</mi>\n <mo>)</mo>\n </mrow>\n <annotation>$(\\mu,\\delta)$</annotation>\n </semantics></math>-limit models over <span></span><math>\n <semantics>\n <msub>\n <mi>M</mi>\n <mn>0</mn>\n </msub>\n <annotation>$M_0$</annotation>\n </semantics></math>, respectively, we have that <span></span><math>\n <semantics>\n <msub>\n <mi>M</mi>\n <mn>1</mn>\n </msub>\n <annotation>$M_1$</annotation>\n </semantics></math> and <span></span><math>\n <semantics>\n <msub>\n <mi>M</mi>\n <mn>2</mn>\n </msub>\n <annotation>$M_2$</annotation>\n </semantics></math> are isomorphic over <span></span><math>\n <semantics>\n <msub>\n <mi>M</mi>\n <mn>0</mn>\n </msub>\n <annotation>$M_0$</annotation>\n </semantics></math>. Note that no tameness is assumed.</p>","PeriodicalId":49864,"journal":{"name":"Mathematical Logic Quarterly","volume":"70 4","pages":"438-453"},"PeriodicalIF":0.4000,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/malq.202200075","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Mathematical Logic Quarterly","FirstCategoryId":"100","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/malq.202200075","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: 0
Abstract
In this paper, we examine the locality condition for non-splitting and determine the level of uniqueness of limit models that can be recovered in some stable, but not superstable, abstract elementary classes. In particular we prove the following. Suppose that is an abstract elementary class satisfying
Then for and limit ordinals both with cofinality , if satisfies symmetry for (or just -symmetry), then, for any and that are and -limit models over , respectively, we have that and are isomorphic over . Note that no tameness is assumed.
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.