{"title":"Another method to add a closed unbounded set of former regulars","authors":"Moti Gitik, Sittinon Jirattikansakul","doi":"10.1007/s00153-026-01008-4","DOIUrl":"10.1007/s00153-026-01008-4","url":null,"abstract":"<div><p>A club consisting of former regulars is added to an inaccessible cardinal, without changing cofinalities outside it. The initial assumption is optimal. A variation of the Radin forcing without a top measurable cardinal is introduced for this.</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"65 4","pages":"509 - 529"},"PeriodicalIF":0.4,"publicationDate":"2026-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147707807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Dominating numbers at singular cardinals","authors":"Yusuke Hayashi","doi":"10.1007/s00153-026-01009-3","DOIUrl":"10.1007/s00153-026-01009-3","url":null,"abstract":"<div><p>We study the generalized dominating number <span>(mathfrak {d}_{mu })</span> at a singular cardinal <span>(mu )</span> of cofinality <span>(kappa )</span>. We prove two basic lower bounds: in <span>(text {ZFC})</span>, <span>(text {cf}left( {[mu ]^kappa ,subseteq }right) le mathfrak {d}_{mu })</span>, and under mild cardinal-arithmetic assumptions, <span>(2^{<mu } le mathfrak {d}_{mu })</span>. We also clarify when <span>(mathfrak {d}_{mu })</span> can differ from <span>(2^mu )</span>: assuming <span>(text {GCH})</span> and <span>(kappa = text {cf}left( {mu }right) > omega )</span>, a finite-support iteration of Cohen forcing of length <span>(mu ^{++})</span> yields <span>(mathfrak {d}_{mu }< 2^mu )</span>. On the other hand, for <span>(kappa = text {cf}left( {mu }right) = omega )</span>, natural <span>(mu )</span>-cc posets force <span>(mathfrak {d}_{mu }= 2^mu .)</span></p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"65 4","pages":"531 - 544"},"PeriodicalIF":0.4,"publicationDate":"2026-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147707804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Monotonicity of the ultrafilter number function","authors":"Toshimichi Usuba","doi":"10.1007/s00153-026-01010-w","DOIUrl":"10.1007/s00153-026-01010-w","url":null,"abstract":"<div><p>We investigate whether the ultrafilter number function <span>(kappa mapsto mathfrak {u}(kappa ))</span> on the cardinals is monotone, that is, whether <span>(mathfrak {u}(lambda ) le mathfrak {u}(kappa ))</span> holds for all cardinals <span>(lambda < kappa )</span> or not. We show that monotonicity can fail, but the failure has large cardinal strength. On the other hand, we prove that there are many restrictions of the failure of monotonicity. For instance, if <span>(kappa )</span> is a singular cardinal with countable cofinality or a strong limit singular cardinal, then <span>(mathfrak {u}(kappa ) le mathfrak {u}(kappa ^+))</span> holds.</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"65 4","pages":"545 - 568"},"PeriodicalIF":0.4,"publicationDate":"2026-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00153-026-01010-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147707805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bruno Fernando Aceves-Martínez, David J. Fernández-Bretón, L. F. Romero-García, Luis F. Villagómez-Canela
{"title":"The adjacent Hindman’s Theorem and the (mathbb Z)-Ramsey’s Theorem","authors":"Bruno Fernando Aceves-Martínez, David J. Fernández-Bretón, L. F. Romero-García, Luis F. Villagómez-Canela","doi":"10.1007/s00153-026-01004-8","DOIUrl":"10.1007/s00153-026-01004-8","url":null,"abstract":"<div><p>We consider the restriction of Ramsey’s theorem that arises from considering only translation-invariant colourings of pairs, and show that this has the same strength (both from the viewpoint of Reverse Mathematics and from the viewpoint of Computability Theory) as the <i>Adjacent Hindman’s Theorem</i>, proposed by L. Carlucci (Arch. Math. Log. <b>57</b> (2018), 381–359). We also investigate some higher dimensional versions of both of these statements.</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"65 4","pages":"451 - 463"},"PeriodicalIF":0.4,"publicationDate":"2026-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147707806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Small measurable cardinals","authors":"Yair Hayut, Asaf Karagila","doi":"10.1007/s00153-026-01006-6","DOIUrl":"10.1007/s00153-026-01006-6","url":null,"abstract":"<div><p>We continue the work from [8] and make a small—but significant—improvement to the definition of <i>j</i>-decomposable system. This provides us with a better lifting of elementary embeddings to symmetric extensions. In particular, this allows us to more easily lift weakly compact embeddings and thus preserve the notion of weakly critical cardinals. We use this improved lifting criterion to show that the first measurable cardinal can be the first weakly critical cardinal or the first Mahlo cardinal, both relative to the existence of a single measurable cardinal. However, if the first inaccessible cardinal is the first measurable cardinal, then in a suitable inner model it has Mitchell order of at least 2.</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"65 4","pages":"465 - 475"},"PeriodicalIF":0.4,"publicationDate":"2026-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00153-026-01006-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147707802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Borel complexity of families of finite equivalence relations via large cardinals","authors":"Michael C. Laskowski, Danielle S. Ulrich","doi":"10.1007/s00153-026-01007-5","DOIUrl":"10.1007/s00153-026-01007-5","url":null,"abstract":"<div><p>We consider a large family of theories of equivalence relations, each with finitely many classes, and assuming the existence of an <span>(omega )</span>-Erdős cardinal, we determine which of these theories are Borel complete. We develop machinery, including <i>forbidding nested sequences</i> which implies a tight upper bound on Borel complexity, and <i>admitting cross-cutting absolutely indiscernible sets</i> which in our context implies Borel completeness.</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"65 4","pages":"477 - 508"},"PeriodicalIF":0.4,"publicationDate":"2026-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00153-026-01007-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147707803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Characterization of subdirectly irreducible heyting algebras with negative tense operators","authors":"Federico Almiñana, Gustavo Pelaitay","doi":"10.1007/s00153-025-01001-3","DOIUrl":"10.1007/s00153-025-01001-3","url":null,"abstract":"<div><p>In (Intuitionistic propositional logic with galois negations. Stud Logica 111:21–56, 2023) , Ma and Li established Intuitionistic Propositional Logic with Galois negations (IGN). These logics can be viewed as the ordered dualization of Ewald’s intuitionistic tense logic IKt, where Galois negations function as the ordered duals of residuated pairs of tense operators. In Almiñana et al. (On heyting algebras with negative tense operators. Stud Logica 111:1015–1036, 2023), we introduced the concept of negative tense operators on Heyting algebras and defined the variety of tense H-algebras. This new variety of algebras serves as the algebraic semantics for IGN. In this paper, we extend our investigation into tense H-algebras, focusing specifically on their topological properties. Particularly, we provide a topological characterization of subdirectly irreducible tense H-algebras.\u0000</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"65 3","pages":"425 - 449"},"PeriodicalIF":0.4,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147618013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Limits on forcing axioms at (omega _2) compatible with the continuum hypothesis","authors":"Stevo Todorcevic, Shihao Xiong","doi":"10.1007/s00153-025-01003-1","DOIUrl":"10.1007/s00153-025-01003-1","url":null,"abstract":"<div><p>We show that the forcing axiom for countably compact, <span>(omega _2)</span>-Knaster, well-met posets is inconsistent. This is supplemental to an inconsistency result of Shelah [9] and sets a new limit to the generalization of Martin’s Axiom to the stage of <span>(omega _2)</span>.</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"65 3","pages":"411 - 423"},"PeriodicalIF":0.4,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147617978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Logical complexity of reducts of elementary algebraic classes","authors":"Carles Cardó","doi":"10.1007/s00153-025-01002-2","DOIUrl":"10.1007/s00153-025-01002-2","url":null,"abstract":"<div><p>We examine how elementary classes of algebras can be represented as reducts of logically simpler classes. For example, we demonstrate that every elementary class is a reduct of a positive class, and that any variety is a reduct of a four-based variety. Additionally, we introduce hierarchies based on fragments of first-order logic to analyse these reducts, providing a more detailed structural understanding of the landscape of algebraic classes.</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"65 3","pages":"391 - 409"},"PeriodicalIF":0.4,"publicationDate":"2025-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147617977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A general approach to asymptotic elimination of aggregation functions and generalized quantifiers","authors":"Vera Koponen, Felix Weitkämper","doi":"10.1007/s00153-025-01000-4","DOIUrl":"10.1007/s00153-025-01000-4","url":null,"abstract":"<div><p>We consider a logic with truth values in the unit interval and which uses aggregation functions instead of quantifiers, and we describe a general approach to asymptotic elimination of aggregation functions and, indirectly, of asymptotic elimination of Mostowski style generalized quantifiers, since such can be expressed by using aggregation functions. The notion of “local continuity” of an aggregation function, which we make precise in two (related) ways, plays a central role in this approach.</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"65 3","pages":"363 - 390"},"PeriodicalIF":0.4,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00153-025-01000-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147618014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}