{"title":"The Chermak–Delgado measure as a map on posets","authors":"William Cocke, Ryan McCulloch","doi":"10.1007/s00013-024-02015-8","DOIUrl":"10.1007/s00013-024-02015-8","url":null,"abstract":"<div><p>The Chermak–Delgado measure of a finite group is a function which assigns to each subgroup a positive integer. In this paper, we give necessary and sufficient conditions for when the Chermak–Delgado measure of a group is actually a map of posets, i.e., a monotone function from the subgroup lattice to the positive integers. We also investigate when the Chermak–Delgado measure, restricted to the centralizers, is increasing.</p></div>","PeriodicalId":8346,"journal":{"name":"Archiv der Mathematik","volume":"123 3","pages":"241 - 251"},"PeriodicalIF":0.5,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00013-024-02015-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142205983","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":"Rigidity of solutions to elliptic equations with one uniform limit","authors":"Phuong Le","doi":"10.1007/s00013-024-02040-7","DOIUrl":"10.1007/s00013-024-02040-7","url":null,"abstract":"<div><p>Let <span>(uge -1)</span> be a solution to the semilinear elliptic equation <span>(-Delta u = f(u))</span> in <span>(mathbb {R}^N)</span> such that <span>(lim _{x_Nrightarrow -infty } u(x',x_N) = -1)</span> uniformly in <span>(x'in mathbb {R}^{N-1})</span>, <span>(lim _{trightarrow +infty } inf _{x_N>t} u(x) > -1)</span>, and <i>u</i> is bounded in each half-space <span>({x_N<lambda })</span>, <span>(lambda in mathbb {R})</span>. Here <span>(f:[-1,+infty )rightarrow mathbb {R})</span> is a locally Lipschitz continuous function which satisfies some mild assumptions. We show that <i>u</i> is strictly monotonically increasing in the <span>(x_N)</span>-direction. Under some further assumptions on <i>f</i>, we deduce that <i>u</i> depends only on <span>(x_N)</span> and it is unique up to a translation. In particular, such a solution <i>u</i> to the problem <span>(Delta u = u + 1)</span> in <span>(mathbb {R}^N)</span> must have the form <span>(u(x)equiv e^{x_N+alpha }-1)</span> for some <span>(alpha in mathbb {R})</span>.</p></div>","PeriodicalId":8346,"journal":{"name":"Archiv der Mathematik","volume":"123 5","pages":"531 - 542"},"PeriodicalIF":0.5,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206095","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 remark on the norm of the parallel sum","authors":"Ali Zamani","doi":"10.1007/s00013-024-02048-z","DOIUrl":"10.1007/s00013-024-02048-z","url":null,"abstract":"<div><p>It is shown that if <span>(a!:!b)</span> is the parallel sum of the two positive definite elements <i>a</i> and <i>b</i> of a <span>(C^*)</span>-algebra, then for any <span>(s, tin [0, 1])</span>, </p><div><div><span>$$begin{aligned} big Vert a!:!bbig Vert le frac{1}{2}left( Vert aVert !:!Vert bVert + frac{Vert aVert :Vert bVert }{Vert aVert +Vert bVert }sqrt{left( Vert aVert -Vert bVert right) ^2 +4left| a^{1-s}b^{t}right| left| a^{s}b^{1-t}right| },right) . end{aligned}$$</span></div></div><p>This inequality, which is sharper than the inequality <span>(big Vert a!:!bbig Vert le Vert aVert !:!Vert bVert )</span>, generalizes an earlier related inequality.</p></div>","PeriodicalId":8346,"journal":{"name":"Archiv der Mathematik","volume":"123 6","pages":"635 - 639"},"PeriodicalIF":0.5,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206096","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":"One-dimensional quasi-uniform Kronecker sequences","authors":"Takashi Goda","doi":"10.1007/s00013-024-02039-0","DOIUrl":"10.1007/s00013-024-02039-0","url":null,"abstract":"<div><p>In this short note, we prove that the one-dimensional Kronecker sequence <span>(ialpha bmod 1, i=0,1,2,ldots ,)</span> is quasi-uniform over the unit interval [0, 1] if and only if <span>(alpha )</span> is a badly approximable number. Our elementary proof relies on a result on the three-gap theorem for Kronecker sequences due to Halton (Proc Camb Philos Soc, 61:665–670, 1965).</p></div>","PeriodicalId":8346,"journal":{"name":"Archiv der Mathematik","volume":"123 5","pages":"499 - 505"},"PeriodicalIF":0.5,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00013-024-02039-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206097","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":"Common substring with shifts in b-ary expansions","authors":"Xin Liao, Dingding Yu","doi":"10.1007/s00013-024-02038-1","DOIUrl":"10.1007/s00013-024-02038-1","url":null,"abstract":"<div><p>Denote by <span>(S_n(x,y))</span> the length of the longest common substring of <i>x</i> and <i>y</i> with shifts in their first <i>n</i> digits of the <i>b</i>-ary expansions. We show that the sets of pairs (<i>x</i>, <i>y</i>), for which the growth rate of <span>(S_n(x,y))</span> is <span>(alpha log n)</span> with <span>(0le alpha le infty )</span>, have full Hausdorff dimension. Our method relies upon some estimation of the spectral radius of matrices.</p></div>","PeriodicalId":8346,"journal":{"name":"Archiv der Mathematik","volume":"123 4","pages":"369 - 377"},"PeriodicalIF":0.5,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141935933","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 note on parallel mean curvature surfaces and Codazzi operators","authors":"Felippe Guimarães","doi":"10.1007/s00013-024-02043-4","DOIUrl":"10.1007/s00013-024-02043-4","url":null,"abstract":"<div><p>We use an intrinsic Klotz–Osserman type result for surfaces in terms of Codazzi operators to study surfaces with parallel mean curvature and non-positive Gaussian curvature in product spaces.</p></div>","PeriodicalId":8346,"journal":{"name":"Archiv der Mathematik","volume":"123 5","pages":"557 - 566"},"PeriodicalIF":0.5,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141935929","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":"Rotationally symmetric gradient Yamabe solitons","authors":"Antonio W. Cunha, Rong Mi","doi":"10.1007/s00013-024-02032-7","DOIUrl":"10.1007/s00013-024-02032-7","url":null,"abstract":"<div><p>This short note deals with compact and complete and non-compact gradient Yamabe solitons (<i>M</i>, <i>g</i>, <i>f</i>) such that it has metric of constant scalar curvature. Firstly, we give a new proof of triviality for gradient compact Yamabe solitons. Also, under some integral conditions, we are able to improve a result due to Ma and Miquel (Ann Global Anal Geom 42:195–205, 2012). Finally, we obtain that the Yamabe metric becomes rotationally symmetric. Results for <i>k</i>-Yamabe solitons are also obtained here.</p></div>","PeriodicalId":8346,"journal":{"name":"Archiv der Mathematik","volume":"123 4","pages":"447 - 453"},"PeriodicalIF":0.5,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141935930","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":"An improvement of the sharp Li–Yau bound on closed manifolds","authors":"Jia-Yong Wu","doi":"10.1007/s00013-024-02027-4","DOIUrl":"10.1007/s00013-024-02027-4","url":null,"abstract":"<div><p>In this paper, we give a generalization of Zhang’s recent work about a sharp Li–Yau gradient bound on compact manifolds by extending Hamilton’s gradient estimates. In particular, we take a special auxiliary function to indicate that our estimate is a slight improvement of Zhang’s result.</p></div>","PeriodicalId":8346,"journal":{"name":"Archiv der Mathematik","volume":"123 3","pages":"309 - 318"},"PeriodicalIF":0.5,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141935931","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":"Partial Dedekind zeta values for ideal classes of the real quadratic field ({mathbb {Q}})((sqrt{9m^{2}+2m}))","authors":"Ahmad Issa, Boushra Darrag","doi":"10.1007/s00013-024-02037-2","DOIUrl":"10.1007/s00013-024-02037-2","url":null,"abstract":"<div><p>In this paper, we obtain some of the partial Dedekind zeta values for ideal classes of the real quadratic field <span>({mathbb {Q}})</span>(<span>(sqrt{D}))</span>, where <span>(D = 9m^{2}+2m)</span> is a square-free positive integer and <span>(m equiv 2)</span> (mod 3) is an odd positive integer.</p></div>","PeriodicalId":8346,"journal":{"name":"Archiv der Mathematik","volume":"123 4","pages":"379 - 383"},"PeriodicalIF":0.5,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141935935","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":"Combinatorial constructions of repairable threshold schemes","authors":"Jinghui Zhao, Xiuling Shan, Zihong Tian, Guohui Hao","doi":"10.1007/s00013-024-02034-5","DOIUrl":"10.1007/s00013-024-02034-5","url":null,"abstract":"<div><p>A repairable threshold scheme is a threshold scheme in which a player can securely reconstruct a lost share with the help from a subset of players. In 2018, Stinson and Wei proposed distribution designs to construct repairable threshold schemes. In this paper, we use packing quadruples as distribution designs to distribute subshares of a ramp scheme. The resulting repairable threshold scheme has lower computational complexity and repairing degree.</p></div>","PeriodicalId":8346,"journal":{"name":"Archiv der Mathematik","volume":"123 4","pages":"353 - 366"},"PeriodicalIF":0.5,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141935934","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}