{"title":"Fixed point theorem for generalized Chatterjea type mappings","authors":"C. M. Păcurar, O. Popescu","doi":"10.1007/s10474-024-01455-6","DOIUrl":"10.1007/s10474-024-01455-6","url":null,"abstract":"<div><p>We introduce a new type of mappings in metric spaces which are\u0000three-point analogue of the well-known Chatterjea type mappings, and call them\u0000generalized Chatterjea type mappings. It is shown that such mappings can be \u0000discontinuous as is the case of Chatterjea type mappings and this new class includes\u0000the class of Chatterjea type mappings. The fixed point theorem for generalized\u0000Chatterjea type mappings is proven.</p></div>","PeriodicalId":50894,"journal":{"name":"Acta Mathematica Hungarica","volume":"173 2","pages":"500 - 509"},"PeriodicalIF":0.6,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10474-024-01455-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141941491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ellipsephic harmonic series revisited","authors":"J.-P. Allouche, Y. Hu, C. Morin","doi":"10.1007/s10474-024-01448-5","DOIUrl":"10.1007/s10474-024-01448-5","url":null,"abstract":"<div><p>Ellipsephic or Kempner-like harmonic series are series of inverses of integers whose expansion in base <i>B</i>, for some <span>(B geq 2)</span>, contains no occurrence of some fixed digit or some fixed block of digits. A prototypical example was proposed by Kempner in 1914, namely the sum inverses of integers whose expansion in base 10 contains no occurrence of a nonzero given digit. Results about such series address their convergence as well as closed expressions for their sums (or approximations thereof). \u0000Another direction of research is the study of sums of inverses of integers that contain only a given finite number, say <i>k</i>, of some digit or some block of digits, and the limits of such sums when <i>k</i> goes to infinity. \u0000Generalizing partial results in the literature, we give a complete result for any digit or block of digits in any base. \u0000</p></div>","PeriodicalId":50894,"journal":{"name":"Acta Mathematica Hungarica","volume":"173 2","pages":"461 - 470"},"PeriodicalIF":0.6,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141941492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On a preference relation between random variables related to an investment problem","authors":"A.M. Răducan , R. Vernic, G. Zbăganu","doi":"10.1007/s10474-024-01456-5","DOIUrl":"10.1007/s10474-024-01456-5","url":null,"abstract":"<div><p>Related to a stochastic investment problem which aims to deter-mine when is it better to first invest a larger amount of money and afterwards a\u0000smaller one, in this paper we introduce a new preference relation between random\u0000variables. We investigate the link between this new relation and some well-known\u0000stochastic order relations and present some characterization properties illustrated\u0000with numerical examples.</p></div>","PeriodicalId":50894,"journal":{"name":"Acta Mathematica Hungarica","volume":"173 2","pages":"352 - 365"},"PeriodicalIF":0.6,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141941496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Remarks on some cardinal invariants and partition relations","authors":"A. Kumar, S. Shelah","doi":"10.1007/s10474-024-01452-9","DOIUrl":"10.1007/s10474-024-01452-9","url":null,"abstract":"<div><p>We answer some questions about two cardinal invariants associated with separating and almost disjoint families and a partition relation involving indecomposable countable linear orderings.</p></div>","PeriodicalId":50894,"journal":{"name":"Acta Mathematica Hungarica","volume":"173 2","pages":"510 - 524"},"PeriodicalIF":0.6,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141941494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On certain unbounded multiplicative functions in short intervals","authors":"Y. Zhou","doi":"10.1007/s10474-024-01457-4","DOIUrl":"10.1007/s10474-024-01457-4","url":null,"abstract":"<div><p>Recently, Mangerel extended the Matomäki–Radziwiłł theorem to a large collection of unbounded multiplicative functions in typical short intervals. In this paper, we combine Mangerel's result with Halász-type result recently established by Granville, Harper and Soundararajan to consider the distribution of a class of multiplicative functions in short intervals. First, we prove cancellation in the sum of the coefficients of the standard <i>L</i>-function of an automorphic irreducible cuspidal representation of <span>(mathrm{GL}_m)</span> over <span>(mathbb{Q})</span> with unitary central character in typical intervals of length <span>(h(log X)^c)</span> with <span>(h = h(X) rightarrow infty)</span> and some constant <span>(c > 0)</span> (under Vinogradov–Korobov zero-free region and GRC). Then we also establish a non-trivial bound for the product of divisor-bounded multiplicative functions with the Liouville function in arithmetic progressions over typical short intervals.</p></div>","PeriodicalId":50894,"journal":{"name":"Acta Mathematica Hungarica","volume":"173 2","pages":"317 - 339"},"PeriodicalIF":0.6,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141941495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Sharp inequalities involving multiplicative chaos sums","authors":"G.A. Karagulyan","doi":"10.1007/s10474-024-01451-w","DOIUrl":"10.1007/s10474-024-01451-w","url":null,"abstract":"<div><p>The present note is an addition to the author’s recent paper\u0000[44], concerning general multiplicative systems of random variables. Using some\u0000lemmas and the methodology of [13], we obtain a general extremal inequality,\u0000with corollaries involving Rademacher chaos sums and those analogues for multiplicative\u0000systems. In particular we prove that a system of functions generated by\u0000bounded products of a multiplicative system is a convergence system.</p></div>","PeriodicalId":50894,"journal":{"name":"Acta Mathematica Hungarica","volume":"173 2","pages":"340 - 351"},"PeriodicalIF":0.6,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141941493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The ({rm SL}(2,mathbb{C}))-character variety of the Borromean link","authors":"H. Chen, T. Yu","doi":"10.1007/s10474-024-01445-8","DOIUrl":"10.1007/s10474-024-01445-8","url":null,"abstract":"<div><p>For the Borromean link, we determine its irreducible <span>({rm SL}(2,mathbb{C}))</span>-character variety, and find a formula for the twisted Alexander polynomial as a function on the character variety.</p></div>","PeriodicalId":50894,"journal":{"name":"Acta Mathematica Hungarica","volume":"173 2","pages":"414 - 433"},"PeriodicalIF":0.6,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An almost p-standard system of parameters and approximately Cohen–Macaulay modules","authors":"P. H. Nam","doi":"10.1007/s10474-024-01447-6","DOIUrl":"10.1007/s10474-024-01447-6","url":null,"abstract":"<div><p>We characterize the approximate Cohen–Macaulayness of a\u0000module in terms of the length function and the Hilbert coefficient of the module\u0000with respect to an almost p-standard system of parameters (a strict subclass of\u0000d-sequences). As applications, we characterize the approximate Cohen–Macaulay\u0000property of Stanley–Reisner rings, localizations, idealizations, and power series\u0000rings. Furthermore, for power series rings, we construct almost p-standard systems\u0000of parameters of them. From this result, we give a class of Cohen–Macaulay\u0000Rees algebras and give precise formulas computing all Hilbert coefficients of the\u0000formal power series ring with respect to an almost p-standard system of parameters.</p></div>","PeriodicalId":50894,"journal":{"name":"Acta Mathematica Hungarica","volume":"173 2","pages":"366 - 391"},"PeriodicalIF":0.6,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On approximate A-seminorm and A-numerical radius orthogonality of operators","authors":"C. Conde, K. Feki","doi":"10.1007/s10474-024-01439-6","DOIUrl":"10.1007/s10474-024-01439-6","url":null,"abstract":"<div><p>This paper explores the concept of approximate Birkhoff–James orthogonality in the context of operators on semi-Hilbert spaces. These spaces are generated by positive semi-definite sesquilinear forms. We delve into the fundamental properties of this concept and provide several characterizations of it. Using innovative arguments, we extend a widely known result initially proposed by Magajna [17]. Additionally, we improve a recent result by Sen and Paul [24] regarding a characterization of approximate numerical radius orthogonality of two semi-Hilbert space operators, such that one of them is <span>(A)</span>-positive. Here, <span>(A)</span> is assumed to be a positive semi-definite operator.</p></div>","PeriodicalId":50894,"journal":{"name":"Acta Mathematica Hungarica","volume":"173 1","pages":"227 - 245"},"PeriodicalIF":0.6,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141549243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Cabello, É Czabarka, R. Fabila-Monroy, Y. Higashikawa, R. Seidel, L. Székely, J. Tkadlec, A. Wesolek
{"title":"A note on the 2-colored rectilinear crossing number of random point sets in the unit square","authors":"S. Cabello, É Czabarka, R. Fabila-Monroy, Y. Higashikawa, R. Seidel, L. Székely, J. Tkadlec, A. Wesolek","doi":"10.1007/s10474-024-01436-9","DOIUrl":"10.1007/s10474-024-01436-9","url":null,"abstract":"<div><p>Let <span>(S)</span> be a set of four points chosen independently, uniformly at random from a square. Join every pair of points of <span>(S)</span> with a straight line segment. Color these edges red if they have positive slope and blue, otherwise. We show that the probability that <span>(S)</span> defines a pair of crossing edges of the same color is equal to <span>(1/4)</span>. This is connected to a recent result of Aichholzer et al. [1] who showed that by 2-colouring the edges of a geometric graph and counting monochromatic crossings instead of crossings, the number of crossings can be more than halved. \u0000Our result shows that for the described random drawings, there is a coloring of the edges such that the number of monochromatic crossings is in expectation <span>(frac{1}{2}-frac{7}{50})</span> of the total number of crossings.</p></div>","PeriodicalId":50894,"journal":{"name":"Acta Mathematica Hungarica","volume":"173 1","pages":"214 - 226"},"PeriodicalIF":0.6,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10474-024-01436-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141549244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}