{"title":"Balanced Stirling numbers","authors":"Michael Maltenfort","doi":"10.1007/s00010-024-01087-9","DOIUrl":"10.1007/s00010-024-01087-9","url":null,"abstract":"<div><p>Hsu and Shiue (Adv Appl Math 20(3):366–384, 1998. https://doi.org/10.1006/aama.1998.0586) defined generalized Stirling numbers, which include as special cases a wide variety of combinatorial quantities. We prove that the two kinds of central factorial numbers are fundamentally different new special cases. Our approach also yields a previously unrecognized connection between the two kinds of central factorial numbers. In order to prove our main results, we introduce balanced Stirling numbers, which specialize the generalized Stirling numbers and can be further specialized into either kind of central factorial numbers.</p></div>","PeriodicalId":55611,"journal":{"name":"Aequationes Mathematicae","volume":"99 2","pages":"705 - 731"},"PeriodicalIF":0.9,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141572684","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":"A Kannappan-sine addition law on semigroups","authors":"Jafar Ahmed, Ajebbar Omar, Elqorachi Elhoucien","doi":"10.1007/s00010-024-01104-x","DOIUrl":"10.1007/s00010-024-01104-x","url":null,"abstract":"<div><p>Let <i>S</i> be a semigroup and <span>(z_{0})</span> a fixed element in <i>S</i>. We determine the complex-valued solutions of the following Kannappan-sine addition law <span>(f(xyz_{0})=f(x)g(y)+f(y)g(x),x,yin S.)</span></p></div>","PeriodicalId":55611,"journal":{"name":"Aequationes Mathematicae","volume":"98 4","pages":"1001 - 1017"},"PeriodicalIF":0.9,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141546759","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":"Set-valued dynamics related to convex-valued m-mappings","authors":"Hamid Khodaei","doi":"10.1007/s00010-024-01103-y","DOIUrl":"10.1007/s00010-024-01103-y","url":null,"abstract":"<div><p>In this article, we study the set-valued dynamics related to some Euler-Lagrange type functional equations of convex-valued <i>m</i>-mappings. We deal with perturbations of these equations. In order to do this, we use the Banach contraction principle and the Hausdorff distance. Several outcomes on approximate solutions of a few important classic equations are discussed and some applications are given.</p></div>","PeriodicalId":55611,"journal":{"name":"Aequationes Mathematicae","volume":"99 2","pages":"741 - 750"},"PeriodicalIF":0.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141546758","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":"Asymptotic expansions of the Archimedean compounds","authors":"Tomislav Burić, Neven Elezović, Lenka Mihoković","doi":"10.1007/s00010-024-01102-z","DOIUrl":"10.1007/s00010-024-01102-z","url":null,"abstract":"<div><p>In this paper we present a complete asymptotic expansion of the Archimedean compound of two symmetric homogeneous means and derive recursive algorithms for coefficients in this expansion. We also show some examples and obtain explicit expansions for the Archimedean compounds of the arithmetic, geometric and harmonic means.</p></div>","PeriodicalId":55611,"journal":{"name":"Aequationes Mathematicae","volume":"98 4","pages":"979 - 999"},"PeriodicalIF":0.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508651","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 surface of Apollonius of two ellipsoids","authors":"Attila Végh","doi":"10.1007/s00010-024-01101-0","DOIUrl":"10.1007/s00010-024-01101-0","url":null,"abstract":"<div><p>Apollonius defined the circle as the set of points that have a given ratio <span>(mu )</span> of distances from two given points, where the ratio is not equal to one. In a more general sense, consider two 0-symmetric, bounded, convex bodies <i>K</i> and <span>(K')</span>, which define two norms. Their unit balls are <i>K</i> and <span>(K')</span>. The surface of Apollonius is defined as the set of points equidistant from the centres of bodies <i>K</i> and <span>(K')</span> with respect to the aforementioned norms. In this paper we demonstrate that the surface of Apollonius of two ellipsoids is a quadratic surface. We also examine the circumstances under which this surface becomes a sphere.</p></div>","PeriodicalId":55611,"journal":{"name":"Aequationes Mathematicae","volume":"98 5","pages":"1333 - 1349"},"PeriodicalIF":0.9,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00010-024-01101-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508652","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":"Mathematical models of functional extreme leaning machins: operator-algebraic and free-probabilistic approaches","authors":"Ilwoo Cho, Palle E. T. Jorgensen","doi":"10.1007/s00010-024-01096-8","DOIUrl":"10.1007/s00010-024-01096-8","url":null,"abstract":"<div><p>In this paper, we establish mathematical models for an arbitrarily fixed functional extreme learning machine (FELM). From a FELM <span>({mathfrak {M}})</span>, we construct a direct graph <i>G</i> induced by <span>({mathfrak {M}})</span>, and then define the graph groupoid <span>({mathbb {G}})</span> of <i>G</i>. Then the graph-groupoid <span>(C^{*})</span>-algebra <span>(M_{G})</span> of <i>G</i> generated by <span>({mathbb {G}})</span> is well-determined. This <span>(C^{*})</span>-algebra <span>(M_{G})</span> is realized on a certain Hilbert space <span>(H_{G})</span> up to a canonical representation. It means that the FELM <span>({mathfrak {M}})</span> is analyzed in a representation-depending structure in terms of operator algebra theory. By defining a natural free probability on <span>(M_{G})</span>, one can have an assessment tool of the operator algebra on <span>(M_{G})</span>, too.</p></div>","PeriodicalId":55611,"journal":{"name":"Aequationes Mathematicae","volume":"99 3","pages":"949 - 988"},"PeriodicalIF":0.9,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141529648","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 generalized notion of metrics","authors":"Wolf-Jürgen Beyn","doi":"10.1007/s00010-024-01092-y","DOIUrl":"10.1007/s00010-024-01092-y","url":null,"abstract":"<div><p>In these notes we generalize the notion of a (pseudo) metric measuring the distance of two points, to a (pseudo) <i>n</i>-metric which assigns a value to a tuple of <span>(n ge 2)</span> points. Some elementary properties of pseudo <i>n</i>-metrics are provided and their construction via exterior products is investigated. We discuss some examples from the geometry of Euclidean vector spaces leading to pseudo <i>n</i>-metrics on the unit sphere, on the Stiefel manifold, and on the Grassmann manifold. Further, we construct a pseudo <i>n</i>-metric on hypergraphs and discuss the problem of generalizing the Hausdorff metric for closed sets to a pseudo <i>n</i>-metric.</p></div>","PeriodicalId":55611,"journal":{"name":"Aequationes Mathematicae","volume":"98 4","pages":"953 - 977"},"PeriodicalIF":0.9,"publicationDate":"2024-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00010-024-01092-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508654","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":"Uniformly-like convex solutions for the polynomial-like iterative equation in Banach spaces","authors":"Hou Yu Zhao, Meng Lian Xia","doi":"10.1007/s00010-024-01099-5","DOIUrl":"10.1007/s00010-024-01099-5","url":null,"abstract":"<div><p>Using Schauder’s fixed point theorem and the Banach contraction principle, the existence, uniqueness, and stability of monotone solutions and uniformly-like convex solutions of the polynomial-like iterative functional equation are studied in Banach spaces. Furthermore, the approximate solutions of the corresponding solutions are considered. Some examples are considered for our results.</p></div>","PeriodicalId":55611,"journal":{"name":"Aequationes Mathematicae","volume":"99 1","pages":"199 - 221"},"PeriodicalIF":0.9,"publicationDate":"2024-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521862","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":"A Kannappan-sine subtraction law on semigroups","authors":"Ahmed Jafar, Omar Ajebbar, Elhoucien Elqorachi","doi":"10.1007/s00010-024-01098-6","DOIUrl":"10.1007/s00010-024-01098-6","url":null,"abstract":"<div><p>Let <i>S</i> be a semigroup, <span>(z_0)</span> a fixed element in <i>S</i> and <span>(sigma :S longrightarrow S)</span> an involutive automorphism. We determine the complex-valued solutions of the Kannappan-sine subtraction law </p><div><div><span>$$begin{aligned} f(xsigma (y)z_0)=f(x)g(y)-f(y)g(x),; x,y in S. end{aligned}$$</span></div></div><p>As an application we solve the following variant of the Kannappan-sine subtraction law viz. </p><div><div><span>$$begin{aligned} f(xsigma (y)z_0)=f(x)g(y)-f(y)g(x)+lambda g(xsigma (y)z_0),;x,y in S, end{aligned}$$</span></div></div><p>where <span>(lambda in mathbb {C}^{*})</span>. The continuous solutions on topological semigroups are given and an example to illustrate the main results is also given.</p></div>","PeriodicalId":55611,"journal":{"name":"Aequationes Mathematicae","volume":"99 2","pages":"785 - 804"},"PeriodicalIF":0.9,"publicationDate":"2024-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508653","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":"n-gon centers and central lines","authors":"Marta Farré Puiggalí, Luis Felipe Prieto-Martínez","doi":"10.1007/s00010-024-01100-1","DOIUrl":"10.1007/s00010-024-01100-1","url":null,"abstract":"<div><p>In this paper we provide a review of the concept of center of an <i>n</i>-gon, generalizing the original idea given by C. Kimberling for triangles. We also generalize the concept of central line for <i>n</i>-gons for <span>(nge 3)</span> and establish its basic properties.\u0000</p></div>","PeriodicalId":55611,"journal":{"name":"Aequationes Mathematicae","volume":"98 4","pages":"895 - 919"},"PeriodicalIF":0.9,"publicationDate":"2024-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521863","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}