{"title":"Toughness and the Existence of 2-factors","authors":"Leyou Xu, Bo Zhou","doi":"10.1007/s10114-026-4288-5","DOIUrl":"10.1007/s10114-026-4288-5","url":null,"abstract":"<div><p>In 1985, Enomoto et al. showed that each 2-tough graph with at least three vertices has a 2-factor, but for any <i>ε</i> > 0, there exists a (2 − <i>ε</i>)-tough graph on at least 3 vertices having no 2-factor. In recent years, the study of sufficient conditions for graphs with toughness in [1, 2) having a 2-factor has attracted substantial interest. In this paper, we give new sufficient conditions for a <i>t</i>-tough graph having a 2-factor when <i>t</i> ∈ [1, 2) by involving independence number, minimum degree, connectivity and forbidden forests, improving and extending some known results.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"42 9","pages":"2241 - 2251"},"PeriodicalIF":0.9,"publicationDate":"2026-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149007356","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}
Houshan Fu, Baoren Peng, Suijie Wang, Jinxing Yang
{"title":"Two Bijections on NBC Subsets","authors":"Houshan Fu, Baoren Peng, Suijie Wang, Jinxing Yang","doi":"10.1007/s10114-026-4536-8","DOIUrl":"10.1007/s10114-026-4536-8","url":null,"abstract":"<div><p>We establish two explicit bijections: from acyclic reorientations of an oriented matroid to no broken circuit (NBC) subsets of its underlying matroid, and from regions of a real hyperplane arrangement to its affine NBC subsets.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"42 9","pages":"2281 - 2294"},"PeriodicalIF":0.9,"publicationDate":"2026-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149007380","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 Average Behavior of Fourier Coefficients of j-th Symmetric Power L-function over Certain Sequences","authors":"Youjun Wang","doi":"10.1007/s10114-026-5406-0","DOIUrl":"10.1007/s10114-026-5406-0","url":null,"abstract":"<div><p>Let <i>j</i> ≥ 2 be a given integer. Let <i>f</i> be a normalized primitive holomorphic cusp form of even integral weight for the full modular group Γ = SL(2, ℤ). Denote by <span>(lambda_{text{sym}^{j}f}(n))</span> the <i>n</i>th normalized coefficient of the Dirichlet expansion of the <i>j</i>th symmetric power <i>L</i>-function <i>L</i>(<i>s</i>, sym<sup><i>j</i></sup><i>f</i>). In this paper, we are interested in the average behavior of <span>(lambda_{text{sym}^{j}f}(n))</span> over some certain sequences, which improved the previous results.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"42 8","pages":"2139 - 2150"},"PeriodicalIF":0.9,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148878120","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":"First Eigenvalue of Embedded Minimal Surfaces in S3","authors":"Yuhang Zhao","doi":"10.1007/s10114-026-5125-6","DOIUrl":"10.1007/s10114-026-5125-6","url":null,"abstract":"<div><p>We prove that for an embedded minimal surface Σ in <i>S</i><sup>3</sup>, the first eigenvalue of the Lapla-cian operator λ<sub>1</sub> satisfies λ<sub>1</sub> ≥ 1 + <i>C</i>(cot<sup>−1</sup> λ<sub>max</sub>)<sup>6</sup>, where λ<sub>max</sub> is the maximum of the (positive) principal curvature and <i>C</i> > 0 is an absolute constant. This improves previous result of Choi–Wang.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"42 8","pages":"2025 - 2037"},"PeriodicalIF":0.9,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148878096","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":"Teodorescu Transform for Slice Monogenic Functions and Applications","authors":"Chao Ding, Zhenghua Xu","doi":"10.1007/s10114-026-5029-5","DOIUrl":"10.1007/s10114-026-5029-5","url":null,"abstract":"<div><p>In the past few years, the theory of slice monogenic functions has been fully developed, especially in its applications to the noncommutative <i>S</i>-functional calculus. In this article, we introduce the Teodorescu transform in the theory of slice monogenic functions, which turns out to be a right inverse of the slice Cauchy–Riemann operator. The boundednesses of the Teodorescu transform and its derivatives are investigated as well. These results successfully generalize the classical results in the complex plane to higher dimensions. As applications, a Hodge decomposition of the Banach space of slice <i>L</i><sup><i>p</i></sup> functions and the corresponding generalized Bergman projection are investigated.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"42 8","pages":"2101 - 2124"},"PeriodicalIF":0.9,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148878122","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":"Banach–Tarski Type Paradox Preserving Self-similar Measure","authors":"Ying Lu, Lifeng Xi","doi":"10.1007/s10114-026-4663-2","DOIUrl":"10.1007/s10114-026-4663-2","url":null,"abstract":"<div><p>In this paper, we obtain a Banach–Tarski type paradox preserving the self-similar measure: Let <i>K</i> be a self-similar set on a complete metric space and <i>ν</i> a self-similar measure on <i>K</i>, then there are bijections <i>g</i><sub><i>i</i></sub>: <i>K</i> → <i>K</i> preserving <i>ν</i>-measure such that </p><div><div><span>$$K = biguplus_{i=1}^{n} A_i = biguplus_{i=1}^{k} g_i(A_i) = biguplus_{i=k+1}^{n} g_i(A_i) quad text{with } k < n,$$</span></div></div><p> where <span>(biguplus)</span> means the disjoint union.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"42 8","pages":"2151 - 2167"},"PeriodicalIF":0.9,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148878121","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":"Commuting Toeplitz and Small Hankel Operators on the Harmonic Bergman Space","authors":"Jie Zhang, Xianfeng Zhao","doi":"10.1007/s10114-026-4467-4","DOIUrl":"10.1007/s10114-026-4467-4","url":null,"abstract":"<div><p>Let <i>φ</i> and <i>ψ</i> be two bounded harmonic functions on the open unit disk, <span>(mathbb{T}_{varphi})</span> and <span>(mathbb{H}_{psi})</span> be the Toeplitz and small Hankel operators on the harmonic Bergman space, respectively. In this paper, we establish a number of necessary conditions and sufficient conditions for <span>(mathbb{T}_{varphi})</span> to commute with <span>(mathbb{H}_{psi})</span>. Moreover, we obtain equivalent characterizations for such commutativity problem in two cases: (i) <i>φ</i> is analytic and <i>ψ</i> is harmonic; (ii) <i>φ</i> is harmonic and the coefficients of the Taylor series of the harmonic function <i>ψ</i> are all real.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"42 8","pages":"2051 - 2072"},"PeriodicalIF":0.9,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148878115","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":"L-function for Sp(4) × GL(2) via a Non-unique Model","authors":"Pan Yan","doi":"10.1007/s10114-026-4579-x","DOIUrl":"10.1007/s10114-026-4579-x","url":null,"abstract":"<div><p>In this paper we prove a conjecture of Ginzburg and Soudry on an integral representation for the <i>L</i>-function <i>L</i><sup><i>S</i></sup>(<i>s, π × τ</i>) attached to a pair (<i>π, τ</i>) of irreducible automorphic cuspidal representations of <span>(text{Sp}_{4}(mathbb{A}))</span> and <span>(text{GL}_{2}(mathbb{A}))</span>, which is derived from the generalized doubling method of Cai, Friedberg, Ginzburg and Kaplan. We show that the integral unfolds to a non-unique model and analyze it using the New Way method of Piatetski-Shapiro and Rallis. Two applications are given. First, we relate the existence of the poles of <i>L</i><sup><i>S</i></sup>(<i>s,π × τ</i>) to the non-vanishing of certain period integrals. Second, for certain family of cuspidal representations, we prove that <i>L</i><sup><i>S</i></sup>(<i>s,π × τ</i>) is holomorphic.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"42 8","pages":"1957 - 1999"},"PeriodicalIF":0.9,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148878117","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 Higher-power Moments of Hecke Eigenvalues for Congruence Group","authors":"Jing Huang, Wenguang Zhai, Deyu Zhang","doi":"10.1007/s10114-026-4498-x","DOIUrl":"10.1007/s10114-026-4498-x","url":null,"abstract":"<div><p>Let <i>H</i><sub>ℓ</sub>(<i>N</i>) denote the set of normalized primitive holomorphic cusp forms of even integral weight ℓ for the congruence group Γ<sub>0</sub>(<i>N</i>). In this paper, our main goal is to derive asymptotic formulas of </p><div><div><span>$$int_{1}^{T} S_{f}^{l}(x; N) dx,$$</span></div></div><p> where <i>f</i> ∈ <i>H</i><sub>ℓ</sub>(<i>N</i>) and </p><div><div><span>$$S_f(x; N) = sum_{n leq x} lambda_f(n).$$</span></div></div><p>Here <i>λ</i><sub>f</sub>(<i>n</i>) is the <i>n</i>-th Hecke eigenvalue of <i>f</i>.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"42 8","pages":"2073 - 2084"},"PeriodicalIF":0.9,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148878124","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":"(mathscr{F})-Sensitivity for Linear Dynamics and Its Induced Hyperspace Dynamics","authors":"Song-Gwang Won, Jin-Hyon Kim","doi":"10.1007/s10114-026-4462-9","DOIUrl":"10.1007/s10114-026-4462-9","url":null,"abstract":"<div><p>In this paper we study <span>(mathscr{F})</span>-sensitivity for a bounded linear operator <i>T</i> on Banach space and its induced hyperspace dynamics. First, we suggest the necessary and sufficient condition for <span>(mathscr{F})</span>-sensitivity for a bounded linear operator <i>T</i> on Banach space. Next, we consider the natural hyperspace extensions <span>(overline{T})</span> and <span>(tilde{T})</span> of <i>T</i> to the space <i>K</i>(<i>X</i>) of compact subsets of <i>X</i> and <i>C</i>(<i>X</i>) of convex compact subsets of <i>X</i>, respectively. We show that <span>(mathscr{F})</span>-sensitivity is equivalent for the maps <i>T</i>, <span>(overline{T})</span> and <span>(tilde{T})</span>.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"42 8","pages":"2038 - 2050"},"PeriodicalIF":0.9,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148878125","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}