{"title":"On two consequences of CH established by Sierpiński","authors":"R. Pol, P. Zakrzewski","doi":"10.1007/s00153-024-00925-6","DOIUrl":"10.1007/s00153-024-00925-6","url":null,"abstract":"<div><p>We study the relations between two consequences of the Continuum Hypothesis discovered by Wacław Sierpiński, concerning uniform continuity of continuous functions and uniform convergence of sequences of real-valued functions, defined on subsets of the real line of cardinality continuum.</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"63 7-8","pages":"877 - 891"},"PeriodicalIF":0.3,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00153-024-00925-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140885401","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":"Katětov order between Hindman, Ramsey and summable ideals","authors":"Rafał Filipów, Krzysztof Kowitz, Adam Kwela","doi":"10.1007/s00153-024-00924-7","DOIUrl":"10.1007/s00153-024-00924-7","url":null,"abstract":"<div><p>A family <span>(mathcal {I})</span> of subsets of a set <i>X</i> is an <i>ideal on X</i> if it is closed under taking subsets and finite unions of its elements. An ideal <span>(mathcal {I})</span> on <i>X</i> is below an ideal <span>(mathcal {J})</span> on <i>Y</i> in the <i>Katětov order</i> if there is a function <span>(f{: }Yrightarrow X)</span> such that <span>(f^{-1}[A]in mathcal {J})</span> for every <span>(Ain mathcal {I})</span>. We show that the Hindman ideal, the Ramsey ideal and the summable ideal are pairwise incomparable in the Katětov order, where</p><ul>\u0000 <li>\u0000 <p>The <i>Ramsey ideal</i> consists of those sets of pairs of natural numbers which do not contain a set of all pairs of any infinite set (equivalently do not contain, in a sense, any infinite complete subgraph),</p>\u0000 </li>\u0000 <li>\u0000 <p>The <i>Hindman ideal</i> consists of those sets of natural numbers which do not contain any infinite set together with all finite sums of its members (equivalently do not contain IP-sets that are considered in Ergodic Ramsey theory),</p>\u0000 </li>\u0000 <li>\u0000 <p>The <i>summable ideal</i> consists of those sets of natural numbers such that the series of the reciprocals of its members is convergent.\u0000</p>\u0000 </li>\u0000 </ul></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"63 7-8","pages":"859 - 876"},"PeriodicalIF":0.3,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00153-024-00924-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140885588","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":"On undecidability of the propositional logic of an associative binary modality","authors":"Michael Kaminski","doi":"10.1007/s00153-024-00921-w","DOIUrl":"10.1007/s00153-024-00921-w","url":null,"abstract":"<div><p>It is shown that both classical and intuitionistic propositional logics of an associative binary modality are undecidable. The proof is based on the deduction theorem for these logics.</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"63 7-8","pages":"837 - 857"},"PeriodicalIF":0.3,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00153-024-00921-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140811820","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":"Quantifier-free induction for lists","authors":"Stefan Hetzl, Jannik Vierling","doi":"10.1007/s00153-024-00923-8","DOIUrl":"10.1007/s00153-024-00923-8","url":null,"abstract":"<div><p>We investigate quantifier-free induction for Lisp-like lists constructed inductively from the empty list <span>( nil )</span> and the operation <span>({textit{cons}})</span>, that adds an element to the front of a list. First we show that, for <span>(m ge 1)</span>, quantifier-free <span>(m)</span>-step induction does not simulate quantifier-free <span>((m + 1))</span>-step induction. Secondly, we show that for all <span>(m ge 1)</span>, quantifier-free <span>(m)</span>-step induction does not prove the right cancellation property of the concatenation operation on lists defined by left-recursion.\u0000</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"63 7-8","pages":"813 - 835"},"PeriodicalIF":0.3,"publicationDate":"2024-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00153-024-00923-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140624920","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":"Square compactness and Lindelöf trees","authors":"Pedro E. Marun","doi":"10.1007/s00153-024-00918-5","DOIUrl":"10.1007/s00153-024-00918-5","url":null,"abstract":"<div><p>We prove that every weakly square compact cardinal is a strong limit cardinal, and therefore weakly compact. We also study Aronszajn trees with no uncountable finitely splitting subtrees, characterizing them in terms of being Lindelöf with respect to a particular topology. We prove that the class of such trees is consistently non-empty and lies between the classes of Suslin and Aronszajn trees.</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"63 5-6","pages":"741 - 757"},"PeriodicalIF":0.3,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00153-024-00918-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140583135","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":"The Josefson–Nissenzweig theorem and filters on (omega )","authors":"Witold Marciszewski, Damian Sobota","doi":"10.1007/s00153-024-00920-x","DOIUrl":"10.1007/s00153-024-00920-x","url":null,"abstract":"<div><p>For a free filter <i>F</i> on <span>(omega )</span>, endow the space <span>(N_F=omega cup {p_F})</span>, where <span>(p_Fnot in omega )</span>, with the topology in which every element of <span>(omega )</span> is isolated whereas all open neighborhoods of <span>(p_F)</span> are of the form <span>(Acup {p_F})</span> for <span>(Ain F)</span>. Spaces of the form <span>(N_F)</span> constitute the class of the simplest non-discrete Tychonoff spaces. The aim of this paper is to study them in the context of the celebrated Josefson–Nissenzweig theorem from Banach space theory. We prove, e.g., that, for a filter <i>F</i>, the space <span>(N_F)</span> carries a sequence <span>(langle mu _n:nin omega rangle )</span> of normalized finitely supported signed measures such that <span>(mu _n(f)rightarrow 0)</span> for every bounded continuous real-valued function <i>f</i> on <span>(N_F)</span> if and only if <span>(F^*le _K{mathcal {Z}})</span>, that is, the dual ideal <span>(F^*)</span> is Katětov below the asymptotic density ideal <span>({mathcal {Z}})</span>. Consequently, we get that if <span>(F^*le _K{mathcal {Z}})</span>, then: (1) if <i>X</i> is a Tychonoff space and <span>(N_F)</span> is homeomorphic to a subspace of <i>X</i>, then the space <span>(C_p^*(X))</span> of bounded continuous real-valued functions on <i>X</i> contains a complemented copy of the space <span>(c_0)</span> endowed with the pointwise topology, (2) if <i>K</i> is a compact Hausdorff space and <span>(N_F)</span> is homeomorphic to a subspace of <i>K</i>, then the Banach space <i>C</i>(<i>K</i>) of continuous real-valued functions on <i>K</i> is not a Grothendieck space. The latter result generalizes the well-known fact stating that if a compact Hausdorff space <i>K</i> contains a non-trivial convergent sequence, then the space <i>C</i>(<i>K</i>) is not Grothendieck.\u0000</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"63 7-8","pages":"773 - 812"},"PeriodicalIF":0.3,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00153-024-00920-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140583146","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":"Games characterizing certain families of functions","authors":"Marek Balcerzak, Tomasz Natkaniec, Piotr Szuca","doi":"10.1007/s00153-024-00922-9","DOIUrl":"10.1007/s00153-024-00922-9","url":null,"abstract":"<div><p>We obtain several game characterizations of Baire 1 functions between Polish spaces <i>X</i>, <i>Y</i> which extends the recent result of V. Kiss. Then we propose similar characterizations for equi-Bare 1 families of functions. Also, using related ideas, we give game characterizations of Baire measurable and Lebesgue measurable functions.</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"63 7-8","pages":"759 - 772"},"PeriodicalIF":0.3,"publicationDate":"2024-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140583033","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":"The extent of saturation of induced ideals","authors":"Kenta Tsukuura","doi":"10.1007/s00153-024-00919-4","DOIUrl":"10.1007/s00153-024-00919-4","url":null,"abstract":"<div><p>We construct a model with a saturated ideal <i>I</i> over <span>({mathcal {P}}_{kappa }lambda )</span> and study the extent of saturation of <i>I</i>.\u0000</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"63 5-6","pages":"723 - 739"},"PeriodicalIF":0.3,"publicationDate":"2024-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140583145","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":"Herbrandized modified realizability","authors":"Gilda Ferreira, Paulo Firmino","doi":"10.1007/s00153-024-00917-6","DOIUrl":"10.1007/s00153-024-00917-6","url":null,"abstract":"<div><p>Realizability notions in mathematical logic have a long history, which can be traced back to the work of Stephen Kleene in the 1940s, aimed at exploring the foundations of intuitionistic logic. Kleene’s initial realizability laid the ground for more sophisticated notions such as Kreisel’s modified realizability and various modern approaches. In this context, our work aligns with the lineage of realizability strategies that emphasize the accumulation, rather than the propagation of precise witnesses. In this paper, we introduce a new notion of realizability, namely <i>herbrandized modified realizability</i>. This novel form of (cumulative) realizability, presented within the framework of semi-intuitionistic logic is based on a recently developed <i>star combinatory calculus</i>, which enables the gathering of witnesses into nonempty finite sets. We also show that the previous analysis can be extended from logic to (Heyting) arithmetic.</p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"63 5-6","pages":"703 - 721"},"PeriodicalIF":0.3,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00153-024-00917-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140583140","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":"Indiscernibles and satisfaction classes in arithmetic","authors":"Ali Enayat","doi":"10.1007/s00153-024-00915-8","DOIUrl":"10.1007/s00153-024-00915-8","url":null,"abstract":"<div><p>We investigate the theory Peano Arithmetic with Indiscernibles (<span>(textrm{PAI})</span>). Models of <span>(textrm{PAI})</span> are of the form <span>(({mathcal {M}},I))</span>, where <span>({mathcal {M}})</span> is a model of <span>(textrm{PA})</span>, <i>I</i> is an unbounded set of order indiscernibles over <span>({mathcal {M}})</span>, and <span>(({mathcal {M}},I))</span> satisfies the extended induction scheme for formulae mentioning <i>I</i>. Our main results are Theorems A and B following. <b>Theorem A.</b> <i>Let</i> <span>({mathcal {M}})</span> <i>be a nonstandard model of</i> <span>(textrm{PA})</span><i> of any cardinality</i>. <span>(mathcal {M })</span> <i>has an expansion to a model of </i><span>(textrm{PAI})</span> <i>iff</i> <span>( {mathcal {M}})</span> <i>has an inductive partial satisfaction class.</i> Theorem A yields the following corollary, which provides a new characterization of countable recursively saturated models of <span>(textrm{PA})</span>: <b>Corollary.</b> <i>A countable model</i> <span>({mathcal {M}})</span> of <span>(textrm{PA})</span> <i>is recursively saturated iff </i><span>({mathcal {M}})</span> <i>has an expansion to a model of </i><span>(textrm{PAI})</span>. <b>Theorem B.</b> <i>There is a sentence </i><span>(alpha )</span> <i> in the language obtained by adding a unary predicate</i> <i>I</i>(<i>x</i>) <i>to the language of arithmetic such that given any nonstandard model </i><span>({mathcal {M}})</span> <i>of</i> <span>(textrm{PA})</span><i> of any cardinality</i>, <span>({mathcal {M}})</span> <i>has an expansion to a model of </i><span>(text {PAI}+alpha )</span> <i>iff</i> <span>({mathcal {M}})</span> <i>has a inductive full satisfaction class.</i></p></div>","PeriodicalId":48853,"journal":{"name":"Archive for Mathematical Logic","volume":"63 5-6","pages":"655 - 677"},"PeriodicalIF":0.3,"publicationDate":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00153-024-00915-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314057","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}