{"title":"Iterated reduced powers of collapsing algebras","authors":"Miloš S. Kurilić","doi":"10.1016/j.apal.2025.103567","DOIUrl":"10.1016/j.apal.2025.103567","url":null,"abstract":"<div><div><span><math><mrow><mi>rp</mi></mrow><mo>(</mo><mi>B</mi><mo>)</mo></math></span> denotes the reduced power <span><math><msup><mrow><mi>B</mi></mrow><mrow><mi>ω</mi></mrow></msup><mo>/</mo><mi>Φ</mi></math></span> of a Boolean algebra <span><math><mi>B</mi></math></span>, where Φ is the Fréchet filter on <em>ω</em>. We investigate iterated reduced powers (<span><math><msup><mrow><mi>rp</mi></mrow><mrow><mn>0</mn></mrow></msup><mo>(</mo><mi>B</mi><mo>)</mo><mo>=</mo><mi>B</mi></math></span> and <span><math><msup><mrow><mi>rp</mi></mrow><mrow><mi>n</mi><mo>+</mo><mn>1</mn></mrow></msup><mo>(</mo><mi>B</mi><mo>)</mo><mo>=</mo><mrow><mi>rp</mi></mrow><mo>(</mo><msup><mrow><mi>rp</mi></mrow><mrow><mi>n</mi></mrow></msup><mo>(</mo><mi>B</mi><mo>)</mo><mo>)</mo></math></span>) of collapsing algebras and our main intention is to classify the algebras <span><math><msup><mrow><mi>rp</mi></mrow><mrow><mi>n</mi></mrow></msup><mo>(</mo><mrow><mi>Col</mi></mrow><mo>(</mo><mi>λ</mi><mo>,</mo><mi>κ</mi><mo>)</mo><mo>)</mo></math></span>, <span><math><mi>n</mi><mo>≥</mo><mn>1</mn></math></span>, up to isomorphism of their Boolean completions. In particular, assuming that SCH and <span><math><mi>h</mi><mo>=</mo><msub><mrow><mi>ω</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> hold, we show that for any cardinals <span><math><mi>λ</mi><mo>≥</mo><mi>ω</mi></math></span> and <span><math><mi>κ</mi><mo>≥</mo><mn>2</mn></math></span> such that <span><math><mi>κ</mi><mi>λ</mi><mo>></mo><mi>ω</mi></math></span> and <span><math><mrow><mi>cf</mi></mrow><mo>(</mo><mi>λ</mi><mo>)</mo><mo>≤</mo><mi>c</mi></math></span> we have <span><math><mrow><mi>ro</mi></mrow><mo>(</mo><msup><mrow><mi>rp</mi></mrow><mrow><mi>n</mi></mrow></msup><mo>(</mo><mrow><mi>Col</mi></mrow><mo>(</mo><mi>λ</mi><mo>,</mo><mi>κ</mi><mo>)</mo><mo>)</mo><mo>)</mo><mo>≅</mo><mrow><mi>Col</mi></mrow><mo>(</mo><msub><mrow><mi>ω</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msup><mrow><mo>(</mo><msup><mrow><mi>κ</mi></mrow><mrow><mo><</mo><mi>λ</mi></mrow></msup><mo>)</mo></mrow><mrow><mi>ω</mi></mrow></msup><mo>)</mo></math></span>, for each <span><math><mi>n</mi><mo>≥</mo><mn>1</mn></math></span>; more precisely,<span><span><span><math><mrow><mi>ro</mi></mrow><mo>(</mo><msup><mrow><mi>rp</mi></mrow><mrow><mi>n</mi></mrow></msup><mo>(</mo><mrow><mi>Col</mi></mrow><mo>(</mo><mi>λ</mi><mo>,</mo><mi>κ</mi><mo>)</mo><mo>)</mo><mo>)</mo><mo>≅</mo><mrow><mo>{</mo><mtable><mtr><mtd><mrow><mi>Col</mi></mrow><mo>(</mo><msub><mrow><mi>ω</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mi>c</mi><mo>)</mo><mo>,</mo><mspace></mspace></mtd><mtd><mtext> if </mtext><msup><mrow><mi>κ</mi></mrow><mrow><mo><</mo><mi>λ</mi></mrow></msup><mo>≤</mo><mi>c</mi><mo>;</mo></mtd></mtr><mtr><mtd><mrow><mi>Col</mi></mrow><mo>(</mo><msub><mrow><mi>ω</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msup><mrow><mi>κ</mi></mrow><mrow><mo><</mo><mi>λ</mi></mrow></msup><mo>)</mo><mo>,</mo><mspace></mspa","PeriodicalId":50762,"journal":{"name":"Annals of Pure and Applied Logic","volume":"176 6","pages":"Article 103567"},"PeriodicalIF":0.6,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143547846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Automorphism groups of prime models, and invariant measures","authors":"Anand Pillay","doi":"10.1016/j.apal.2025.103568","DOIUrl":"10.1016/j.apal.2025.103568","url":null,"abstract":"<div><div>We adapt the notion from <span><span>[7]</span></span> and <span><span>[2]</span></span> of a (relatively) definable subset of <span><math><mi>A</mi><mi>u</mi><mi>t</mi><mo>(</mo><mi>M</mi><mo>)</mo></math></span> when <em>M</em> is a saturated structure, to the case <span><math><mi>A</mi><mi>u</mi><mi>t</mi><mo>(</mo><mi>M</mi><mo>/</mo><mi>A</mi><mo>)</mo></math></span> when <em>M</em> is atomic and strongly <em>ω</em>-homogeneous (over a set <em>A</em>). We discuss the existence and uniqueness of invariant measures on the Boolean algebra of definable subsets of <span><math><mi>A</mi><mi>u</mi><mi>t</mi><mo>(</mo><mi>M</mi><mo>/</mo><mi>A</mi><mo>)</mo></math></span>. For example when <em>T</em> is stable, we have existence and uniqueness.</div><div>We also discuss the compatibility of our definability notions with definable Galois cohomology from <span><span>[12]</span></span> and differential Galois theory.</div></div>","PeriodicalId":50762,"journal":{"name":"Annals of Pure and Applied Logic","volume":"176 6","pages":"Article 103568"},"PeriodicalIF":0.6,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143547845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Borel sets without perfectly many overlapping translations, III","authors":"Andrzej Rosłanowski , Saharon Shelah","doi":"10.1016/j.apal.2025.103565","DOIUrl":"10.1016/j.apal.2025.103565","url":null,"abstract":"<div><div>We expand the results of Rosłanowski and Shelah <span><span>[11]</span></span>, <span><span>[10]</span></span> to all perfect Abelian Polish groups <span><math><mo>(</mo><mi>H</mi><mo>,</mo><mo>+</mo><mo>)</mo></math></span>. In particular, we show that if <span><math><mi>α</mi><mo><</mo><msub><mrow><mi>ω</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><mn>4</mn><mo>≤</mo><mi>k</mi><mo><</mo><mi>ω</mi></math></span>, then there is a ccc forcing notion adding a <span><math><msubsup><mrow><mi>Σ</mi></mrow><mrow><mn>2</mn></mrow><mrow><mn>0</mn></mrow></msubsup></math></span> set <span><math><mi>B</mi><mo>⊆</mo><mi>H</mi></math></span> which has <span><math><msub><mrow><mi>ℵ</mi></mrow><mrow><mi>α</mi></mrow></msub></math></span> many pairwise <em>k</em>–overlapping translations but not a perfect set of such translations. The technicalities of the forcing construction led us to investigations of the question when, in an Abelian group, <span><math><mi>X</mi><mo>−</mo><mi>X</mi><mo>⊆</mo><mi>Y</mi><mo>−</mo><mi>Y</mi></math></span> imply that a translation of <em>X</em> or −<em>X</em> is included in <em>Y</em>.</div></div>","PeriodicalId":50762,"journal":{"name":"Annals of Pure and Applied Logic","volume":"176 6","pages":"Article 103565"},"PeriodicalIF":0.6,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143547844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Comparing notions of presentability in Polish spaces and Polish groups","authors":"Sapir Ben-Shahar , Heer Tern Koh","doi":"10.1016/j.apal.2025.103564","DOIUrl":"10.1016/j.apal.2025.103564","url":null,"abstract":"<div><div>A recent area of interest in computable topology compares different notions of effective presentability for topological spaces. In this paper, we show that up to isometry, there is a compact connected Polish space that has both left-c.e. and right-c.e. Polish presentations, but has no computable Polish presentation. We also construct a Polish group that has both left-c.e. and right-c.e. Polish group presentations, but lacks a computable Polish presentation, up to topological isomorphism.</div></div>","PeriodicalId":50762,"journal":{"name":"Annals of Pure and Applied Logic","volume":"176 5","pages":"Article 103564"},"PeriodicalIF":0.6,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143463576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Local tabularity is decidable for bi-intermediate logics of trees and of co-trees","authors":"Miguel Martins, Tommaso Moraschini","doi":"10.1016/j.apal.2025.103563","DOIUrl":"10.1016/j.apal.2025.103563","url":null,"abstract":"<div><div>A bi-Heyting algebra validates the Gödel-Dummett axiom <span><math><mo>(</mo><mi>p</mi><mo>→</mo><mi>q</mi><mo>)</mo><mo>∨</mo><mo>(</mo><mi>q</mi><mo>→</mo><mi>p</mi><mo>)</mo></math></span> iff the poset of its prime filters is a disjoint union of co-trees (i.e., order duals of trees). Bi-Heyting algebras of this kind are called <em>bi-Gödel algebras</em> and form a variety that algebraizes the extension <span><math><mi>bi-GD</mi></math></span> of bi-intuitionistic logic axiomatized by the Gödel-Dummett axiom. In this paper we establish the decidability of the problem of determining if a finitely axiomatizable extension of <span><math><mi>bi-GD</mi></math></span> is locally tabular.</div><div>Notably, if <em>L</em> is an axiomatic extension of <span><math><mi>bi-GD</mi></math></span>, then <em>L</em> is locally tabular iff <em>L</em> is not contained in <span><math><mi>L</mi><mi>o</mi><mi>g</mi><mo>(</mo><mi>F</mi><mi>C</mi><mo>)</mo></math></span>, the logic of a particular family of finite co-trees, called the <em>finite combs</em>. We prove that <span><math><mi>L</mi><mi>o</mi><mi>g</mi><mo>(</mo><mi>F</mi><mi>C</mi><mo>)</mo></math></span> is finitely axiomatizable. Since this logic also has the finite model property, it is therefore decidable. Thus, the above characterization of local tabularity ensures the decidability of the aforementioned problem.</div></div>","PeriodicalId":50762,"journal":{"name":"Annals of Pure and Applied Logic","volume":"176 5","pages":"Article 103563"},"PeriodicalIF":0.6,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sergio Celani , Rafał Gruszczyński , Paula Menchón
{"title":"Conditional algebras","authors":"Sergio Celani , Rafał Gruszczyński , Paula Menchón","doi":"10.1016/j.apal.2025.103556","DOIUrl":"10.1016/j.apal.2025.103556","url":null,"abstract":"<div><div>Drawing on the classic paper by Chellas <span><span>[8]</span></span>, we propose a general algebraic framework for studying a binary operation of <em>conditional</em> that models universal features of the “if …, then …” connective as strictly related to the unary modal necessity operator. To this end, we introduce a variety of <em>conditional algebras</em>, and we develop its duality and canonical extensions theory.</div></div>","PeriodicalId":50762,"journal":{"name":"Annals of Pure and Applied Logic","volume":"176 5","pages":"Article 103556"},"PeriodicalIF":0.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143376529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Proof-theoretic methods in quantifier-free definability","authors":"Zoltan A. Kocsis","doi":"10.1016/j.apal.2025.103555","DOIUrl":"10.1016/j.apal.2025.103555","url":null,"abstract":"<div><div>We introduce a proof-theoretic approach to showing nondefinability of second-order intuitionistic connectives by quantifier-free schemata. We apply the method to prove that Taranovsky's “realizability disjunction” connective does not admit a quantifier-free definition, and use it to obtain new results and more nuanced information about the nondefinability of Kreisel's and Połacik's unary connectives. The finitary and combinatorial nature of our method makes it resilient to changes in metatheory, and suitable for settings with axioms that are explicitly incompatible with classical logic. Furthermore, the problem-specific subproofs arising from this approach can be readily transcribed into univalent type theory and verified using the Agda proof assistant.</div></div>","PeriodicalId":50762,"journal":{"name":"Annals of Pure and Applied Logic","volume":"176 4","pages":"Article 103555"},"PeriodicalIF":0.6,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143162322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Generic multiplicative endomorphism of a field","authors":"Christian d'Elbée","doi":"10.1016/j.apal.2025.103554","DOIUrl":"10.1016/j.apal.2025.103554","url":null,"abstract":"<div><div>We introduce the model-companion of the theory of fields expanded by a unary function for a multiplicative endomorphism, which we call ACFH. Among others, we prove that this theory is NSOP<sub>1</sub> and not simple, that the kernel of the map is a generic pseudo-finite abelian group. We also prove that if forking satisfies existence, then ACFH has elimination of imaginaries.</div></div>","PeriodicalId":50762,"journal":{"name":"Annals of Pure and Applied Logic","volume":"176 4","pages":"Article 103554"},"PeriodicalIF":0.6,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143162054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Π2-rule systems and inductive classes of Gödel algebras","authors":"Rodrigo Nicolau Almeida","doi":"10.1016/j.apal.2025.103552","DOIUrl":"10.1016/j.apal.2025.103552","url":null,"abstract":"<div><div>In this paper we present a general theory of <span><math><msub><mrow><mi>Π</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>-rules for systems of intuitionistic and modal logic. We introduce the notions of <span><math><msub><mrow><mi>Π</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>-rule system and of an inductive class, and provide model-theoretic and algebraic completeness theorems, which serve as our basic tools. As an illustration of the general theory, we analyse the structure of inductive classes of Gödel algebras, from a structure theoretic and logical point of view. We show that unlike other well-studied settings (such as logics, or single-conclusion rule systems), there are continuum many <span><math><msub><mrow><mi>Π</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>-rule systems extending <span><math><mrow><mi>LC</mi></mrow><mo>=</mo><mrow><mi>IPC</mi></mrow><mo>+</mo><mo>(</mo><mi>p</mi><mo>→</mo><mi>q</mi><mo>)</mo><mo>∨</mo><mo>(</mo><mi>q</mi><mo>→</mo><mi>p</mi><mo>)</mo></math></span>, and show how our methods allow easy proofs of the admissibility of the well-known Takeuti-Titani rule. Our final results concern general questions admissibility in <span><math><mi>LC</mi></math></span>: (1) we present a full classification of those inductive classes which are inductively complete, i.e., where all <span><math><msub><mrow><mi>Π</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>-rules which are admissible are derivable, and (2) show that the problem of admissibility of <span><math><msub><mrow><mi>Π</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>-rules over <span><math><mi>LC</mi></math></span> is decidable.</div></div>","PeriodicalId":50762,"journal":{"name":"Annals of Pure and Applied Logic","volume":"176 4","pages":"Article 103552"},"PeriodicalIF":0.6,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143162347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Modal logics over lattices","authors":"Xiaoyang Wang , Yanjing Wang","doi":"10.1016/j.apal.2025.103553","DOIUrl":"10.1016/j.apal.2025.103553","url":null,"abstract":"<div><div>Lattice theory has various close connections with modal logic. However, one less explored direction is to view lattices as relational structures based on partial orders, and study the modal logics over them. In this paper, following the earlier steps of Burgess and van Benthem in the 1980s, we use the modal languages of tense logic and polyadic modal logic to talk about lattices via standard Kripke semantics. We first obtain a series of complete axiomatizations of tense logics over lattices, (un)bounded lattices over partial orders or strict orders. In particular, we solve an axiomatization problem left open by Burgess (1984) <span><span>[8]</span></span>. The second half of the paper gives a series of complete axiomatizations of polyadic modal logic with nominals over lattices, distributive lattices, and modular lattices, where the binary modalities of <em>infimum</em> and <em>supremum</em> can reveal more structures behind various lattices.</div></div>","PeriodicalId":50762,"journal":{"name":"Annals of Pure and Applied Logic","volume":"176 4","pages":"Article 103553"},"PeriodicalIF":0.6,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143162323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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