Hui Hui Fang, Dan Jun Huang, Tao Wang, Wei Fan Wang
{"title":"Variable Degeneracy of Planar Graphs without Chorded 6-Cycles","authors":"Hui Hui Fang, Dan Jun Huang, Tao Wang, Wei Fan Wang","doi":"10.1007/s10114-024-2245-8","DOIUrl":"10.1007/s10114-024-2245-8","url":null,"abstract":"<div><p>A cover of a graph <i>G</i> is a graph <i>H</i> with vertex set <i>V</i> (<i>H</i>) = ∪<sub><i>v</i>∈<i>V</i>(<i>G</i>)</sub> <i>L</i><sub><i>v</i></sub>, where <i>L</i><sub><i>v</i></sub> = {<i>v</i>} × [<i>s</i>], and the edge set <i>M</i> = ∪<sub><i>uv</i>∈<i>E</i>(<i>G</i>)</sub> <i>M</i><sub><i>uv</i></sub>, where <i>M</i><sub><i>uv</i></sub> is a matching between <i>L</i><sub><i>u</i></sub> and <i>L</i><sub><i>v</i></sub>. A vertex set <i>T</i> ⊆ <i>V</i> (<i>H</i>) is a transversal of <i>H</i> if ∣<i>T</i> ∩ <i>L</i><sub><i>v</i></sub>∣ = 1 for each <i>v</i> ∈ <i>V</i>(<i>G</i>). Let <i>f</i> be a nonnegative integer valued function on the vertex-set of <i>H</i>. If for any nonempty subgraph Γ of <i>H</i>[<i>T</i>], there exists a vertex <i>x</i> ∈ <i>V</i> (<i>H</i>) such that <i>d</i>(<i>x</i>) < <i>f</i>(<i>x</i>), then <i>T</i> is called a strictly <i>f</i>-degenerate transversal. In this paper, we give a sufficient condition for the existence of strictly <i>f</i>-degenerate transversal for planar graphs without chorded 6-cycles. As a consequence, every planar graph without subgraphs isomorphic to the configurations is DP-4-colorable.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"40 11","pages":"2735 - 2750"},"PeriodicalIF":0.8,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142694744","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 the Centralizers of Rescaling Separating Differentiable Vector Fields","authors":"Bo Han, Xiao Wen","doi":"10.1007/s10114-024-3170-6","DOIUrl":"10.1007/s10114-024-3170-6","url":null,"abstract":"<div><p>In this paper, we introduce a new concept of expansiveness, similar to the separating property. Specifically, we consider a compact Riemannian manifold <i>M</i> without boundary and a <i>C</i><sup>1</sup> vector field <i>X</i> on <i>M</i>, which generates a flow <i>φ</i><sub><i>t</i></sub> on <i>M</i>. We say that <i>X is rescaling separating</i> on a compact invariant set Λ of <i>X</i> if there is a constant <i>δ</i> > 0 such that, for any <i>x</i>, <i>y</i> ∈ Λ, if <i>d</i>(<i>φ</i><sub><i>t</i></sub>(<i>x</i>), <i>φ</i><sub><i>t</i></sub>(<i>y</i>)) ≤ <i>δ</i>∥<i>X</i> (<i>φ</i><sub><i>t</i></sub>(<i>x</i>))∥ for all <i>t</i> ∈ ℝ, then <i>y</i> ∈ Orb(<i>x</i>). We prove that if <i>X</i> is rescaling separating on Λ and every singularity of <i>X</i> in Λ is hyperbolic, then any <i>C</i><sup>1</sup> vector field <i>Y</i>, whose flow commutes with <i>φ</i><sub><i>t</i></sub> on Λ, must be collinear to <i>X</i> on Λ. As applications of this result, we show that the centralizer of a rescaling separating <i>C</i><sup>1</sup> vector field without nonhyperbolic singularity is quasi-trivial. We also proved that there is an open and dense set <span>({cal U} subset {{cal X}^{1}}(M))</span> such that for any star vector field <span>(X in {cal U})</span>, the centralizer of <i>X</i> is collinear to <i>X</i> on the chain recurrent set of <i>X</i>.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"40 11","pages":"2671 - 2683"},"PeriodicalIF":0.8,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142694743","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 Scattered Range Problem of Elementary Operators on ({cal B}({cal H}))","authors":"Peng Cao, Cun Wang","doi":"10.1007/s10114-024-3346-0","DOIUrl":"10.1007/s10114-024-3346-0","url":null,"abstract":"<div><p>A scattered operator is a bounded linear operator with at most countable spectrum. In this paper, we prove that for any elementary operator on <span>({cal B}({cal H}))</span>, not only for finite length but also for infinite length, if the range of the elementary operator is contained in scattered operators, then the corresponding sum of multipliers is a compact operator. We also prove that for some special classes of elementary operators, such as the elementary operators of length 2, higher order inner derivations and generalized inner derivation, if the range of the elementary operator is contained in the set of scattered operators, then the range is contained in the set of power compact operators. At the same time, the multipliers of the corresponding elementary operators are characterized.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"40 11","pages":"2684 - 2692"},"PeriodicalIF":0.8,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142694748","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 Weak ∞-Functor in Morse Theory","authors":"Shan Zhong Sun, Chen Xi Wang","doi":"10.1007/s10114-024-2523-5","DOIUrl":"10.1007/s10114-024-2523-5","url":null,"abstract":"<div><p>In the spirit of Morse homology initiated by Witten and Floer, we construct two ∞-categories <span>({cal A})</span> and <span>({cal B})</span>. The weak one <span>({cal A})</span> comes out of the Morse–Smale pairs and their higher homotopies, and the strict one <span>({cal B})</span> concerns the chain complexes of the Morse functions. Based on the boundary structures of the compactified moduli space of gradient flow lines of Morse functions with parameters, we build up a weak ∞-functor <span>({cal F}:{cal A} rightarrow {cal B})</span>. Higher algebraic structures behind Morse homology are revealed with the perspective of defects in topological quantum field theory.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"40 11","pages":"2571 - 2614"},"PeriodicalIF":0.8,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142694749","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":"Characterizations of Weighted Besov Spaces with Variable Exponents","authors":"Sheng Rong Wang, Peng Fei Guo, Jing Shi Xu","doi":"10.1007/s10114-024-2623-2","DOIUrl":"10.1007/s10114-024-2623-2","url":null,"abstract":"<div><p>In this paper, we first give characterizations of weighted Besov spaces with variable exponents via Peetre’s maximal functions. Then we obtain decomposition characterizations of these spaces by atom, molecule and wavelet. As an application, we obtain the boundedness of the pseudo-differential operators on these spaces.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"40 11","pages":"2855 - 2878"},"PeriodicalIF":0.8,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142694747","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":"Compactness of Extremals for Trudinger-Moser Functionals on the Unit Ball in ℝ2","authors":"Wei Wei Shan, Xiao Meng Li","doi":"10.1007/s10114-024-3046-9","DOIUrl":"10.1007/s10114-024-3046-9","url":null,"abstract":"<div><p>Let <span>(mathbb{B})</span> be a unit ball in ℝ<sup>2</sup>, <span>(W_{0}^{1,2}(mathbb{B}))</span> be the standard Sobolev space. For any <i>ϵ</i> > 0, de Figueiredo, do Ó, dos Santons, Yang and Zhu proved the existence of extremals of a Trudinger-Moser inequality in the unit ball. Precisely, </p><div><div><span>$$mathop {sup }limits_{u in W_0^{1,2}left( mathbb{B} right),int_mathbb{B} {|nabla u{|^2}dx le 1} } int_mathbb{B} {{{left| x right|}^{2epsilon }}{rm{e}^{4pi left( {1 + epsilon } right){u^2}}}} dx$$</span></div></div><p> can be attained by some radially symmetric function <span>(u_{epsilon}in W_{0}^{1,2}(mathbb{B}))</span> with <span>(int_{mathbb{B}}vertnabla u_{epsilon}vert^{2}dx=1)</span>. In this note, we concern the compactness of the function family {<i>u</i><sub><i>ϵ</i></sub>}<sub><i>ϵ</i>>0</sub> and prove that up to a subsequence <i>u</i><sub><i>ϵ</i></sub> converges to some function <i>u</i>\u0000<sub>0</sub> in <span>(C^{1}(overline{mathbb{B}}))</span> as <i>ϵ</i> → 0. Furthermore, <i>u</i><sub>0</sub> is an extremal function of the supremum </p><div><div><span>$$mathop {sup }limits_{u in W_0^{1,2}left( mathbb{B} right),int_mathbb{B} {|nabla u{|^2}dx le 1} } int_{mathbb{B}}rm{e}^{4pi u^{2}}dx.$$</span></div></div><p> Let us explain the result in geometry. Denote <span>(omega_{0}=dx_{1}^{2}+dx_{2}^{2})</span> be the standard Euclidean metric. Define a conical metric <span>(omega_{epsilon}=vert xvert^{2epsilon}omega_{0})</span> for <span>(xinmathbb{B})</span>. Then the extremal family {<i>u</i>\u0000<sub><i>ϵ</i></sub>}<sub><i>ϵ</i>>0</sub> of the following Trudinger-Moser functionals </p><div><div><span>$$int_{mathbb{B}}rm{e}^{4pi(1+epsilon)u^{2}}dv_{w_{epsilon}}$$</span></div></div><p> under the constraint <span>(uin W_{0}^{1,2}(mathbb{B}))</span> and <span>(int_{mathbb{B}}vertnabla_{omega_{epsilon}u}vert^{2}dv_{omega_{epsilon}}leq 1)</span> is compact as <i>ϵ</i> → 0.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"40 11","pages":"2840 - 2854"},"PeriodicalIF":0.8,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142694742","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 pj-rank of Even K-groups of Rings of Integers","authors":"Meng Fai Lim","doi":"10.1007/s10114-024-1312-5","DOIUrl":"10.1007/s10114-024-1312-5","url":null,"abstract":"<div><p>Let <i>L/F</i> be a finite Galois extension of number fields of degree <i>n</i> and let <i>p</i> be a prime which does not divide <i>n</i>. We shall study the <i>p</i><sup><i>j</i></sup>-rank of <span>(K_{2i}(mathcal{O}_{L}))</span> via its Galois module structure following the approaches of Iwasawa and Komatsu–Nakano. Along the way, we generalize previous observations of Browkin, Wu and Zhou on <i>K</i><sub>2</sub>-groups to higher even <i>K</i>-groups. We also give examples to illustrate our results. Finally, we apply our discussion to refine a result of Kitajima pertaining to the <i>p</i>-rank of even <i>K</i>-groups in the cyclotomic ℤ<sub><i>l</i></sub>-extension, where <i>l</i> ≠ <i>p</i>.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"40 10","pages":"2481 - 2496"},"PeriodicalIF":0.8,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142595981","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":"Completeness of Induced Cotorsion Pairs in Representation Categories of Rooted Quivers","authors":"Zhen Xing Di, Li Ping Li, Li Liang, Fei Xu","doi":"10.1007/s10114-024-3041-1","DOIUrl":"10.1007/s10114-024-3041-1","url":null,"abstract":"<div><p>This paper focuses on a question raised by Holm and Jørgensen, who asked if the induced cotorsion pairs (Φ(X), Φ(X)<sup>⊥</sup>) and (<sup>⊥</sup>Ψ(Y), Ψ(Y)) in Rep(<i>Q</i>, A)—the category of all A-valued representations of a quiver <i>Q</i>—are complete whenever (X, Y) is a complete cotorsion pair in an abelian category A satisfying some mild conditions. We give an affirmative answer if the quiver <i>Q</i> is rooted. As an application, we show under certain mild conditions that if a subcategory L, which is not necessarily closed under direct summands, of A is special precovering (resp., preenveloping), then Φ(L)(resp., Ψ(L)) is special precovering (resp., preenveloping) in Rep(<i>Q</i>, A).</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"40 10","pages":"2436 - 2452"},"PeriodicalIF":0.8,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141824347","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 Some Sums Involving Small Arithmetic Functions","authors":"Wen Guang Zhai","doi":"10.1007/s10114-024-2129-y","DOIUrl":"10.1007/s10114-024-2129-y","url":null,"abstract":"<div><p>Let <i>f</i> be any arithmetic function and define <span>({S_{f}}(x):=sumnolimits_{{n le x}}f([x/n]))</span>. If the function <i>f</i> is small, namely, <i>f</i>(<i>n</i>) ≪ <i>n</i><sup><i>ε</i></sup>, then the error term <i>E</i><sub><i>f</i></sub>(<i>x</i>) in the asymptotic formula of <i>S</i><sub><i>f</i></sub>(<i>x</i>) has the form <i>O</i>(<i>x</i><sup>1/2+<i>ε</i></sup>). In this paper, we shall study the mean square of <i>E</i><sub><i>f</i></sub>(<i>x</i>) and establish some new results of <i>E</i><sub><i>f</i></sub>(<i>x</i>) for some special functions.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"40 10","pages":"2497 - 2518"},"PeriodicalIF":0.8,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141825074","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":"Supnorm Estimates for ({bar partial}) on Product Domains in ℂn","authors":"Martino Fassina, Yi Fei Pan","doi":"10.1007/s10114-024-2463-0","DOIUrl":"10.1007/s10114-024-2463-0","url":null,"abstract":"<div><p>Using methods from complex analysis in one variable, we define an integral operator that solves <span>({bar partial})</span> with supnorm estimates on product domains in ℂ<sup><i>n</i></sup>.</p></div>","PeriodicalId":50893,"journal":{"name":"Acta Mathematica Sinica-English Series","volume":"40 10","pages":"2307 - 2323"},"PeriodicalIF":0.8,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141825922","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}