Pub Date : 2024-06-03DOI: 10.21136/cmj.2024.0065-23
Yang Wang, Weifan Wang, Jiangxu Kong, Yiqiao Wang
{"title":"Partitioning a planar graph without chordal 5-cycles into two forests","authors":"Yang Wang, Weifan Wang, Jiangxu Kong, Yiqiao Wang","doi":"10.21136/cmj.2024.0065-23","DOIUrl":"https://doi.org/10.21136/cmj.2024.0065-23","url":null,"abstract":"","PeriodicalId":50596,"journal":{"name":"Czechoslovak Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141272330","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}
Pub Date : 2024-05-31DOI: 10.21136/cmj.2024.0332-23
Bappaditya Bhowmik, Sambhunath Sen
It is known that if f is holomorphic in the open unit disc (mathbb{D}) of the complex plane and if, for some c > 0, ∣f(z)∣ ⩽ 1/(1−∣z∣2)c, (z in mathbb{D}), then ∣f′(z)∣ ⩽ 2(c+1)/(1−∣z∣2)c+1. We consider a meromorphic analogue of this result. Furthermore, we introduce and study the class of meromorphic Bloch-type functions that possess a nonzero simple pole in D. In particular, we obtain bounds for the modulus of the Taylor coefficients of functions in this class.
众所周知,如果 f 在复平面的开放单位圆盘 (mathbb{D})中是全态的,并且对于某些 c >;0,∣f(z)∣ ⩽ 1/(1-∣z∣2)c, (z in mathbb{D}),那么∣f′(z)∣ ⩽ 2(c+1)/(1-∣z∣2)c+1。我们考虑了这一结果的分形类似物。此外,我们还引入并研究了一类在 D 中具有非零简单极点的布洛赫类函数。
{"title":"Bounds for the derivative of certain meromorphic functions and on meromorphic Bloch-type functions","authors":"Bappaditya Bhowmik, Sambhunath Sen","doi":"10.21136/cmj.2024.0332-23","DOIUrl":"https://doi.org/10.21136/cmj.2024.0332-23","url":null,"abstract":"<p>It is known that if f is holomorphic in the open unit disc <span>(mathbb{D})</span> of the complex plane and if, for some <i>c</i> > 0, ∣<i>f</i>(<i>z</i>)∣ ⩽ 1/(1−∣<i>z</i>∣<sup>2</sup>)<sup><i>c</i></sup>, <span>(z in mathbb{D})</span>, then ∣<i>f</i>′(<i>z</i>)∣ ⩽ 2(<i>c</i>+1)/(1−∣<i>z</i>∣<sup>2</sup>)<sup><i>c</i>+1</sup>. We consider a meromorphic analogue of this result. Furthermore, we introduce and study the class of meromorphic Bloch-type functions that possess a nonzero simple pole in D. In particular, we obtain bounds for the modulus of the Taylor coefficients of functions in this class.</p>","PeriodicalId":50596,"journal":{"name":"Czechoslovak Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141501950","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}
Pub Date : 2024-05-30DOI: 10.21136/cmj.2024.0394-21
Min Chen, André Raspaud, Weifan Wang, Weiqiang Yu
Given a graph G = (V, E), if we can partition the vertex set V into two nonempty subsets V1 and V2 which satisfy Δ(G[V1]) ⩽ d1 and Δ(G[V2]) ⩽ d2, then we say G has a (({{rm{Delta }}_{{d_1}}},,{{rm{Delta }}_{{d_2}}}))-partition. And we say G admits an (({F_{d_{1}}}, {F_{d_{2}}}))-partition if G[V1] and G[V2] are both forests whose maximum degree is at most d1 and d2, respectively. We show that every planar graph with girth at least 5 has an (F4, F4)-partition.
给定一个图 G = (V,E),如果我们可以将顶点集 V 分成两个非空子集 V1 和 V2,且这两个子集满足 Δ(G[V1]) ⩽ d1 和 Δ(G[V2]) ⩽ d2、那么我们说 G 有一个 (({{rm{Delta }}_{d_1}}},,{{rm{Delta }}_{d_2}}))-partition.如果 G[V1] 和 G[V2] 都是最大度分别最多为 d1 和 d2 的森林,我们就说 G 有一个 (({F_{d_{1}}}, {F_{d_{2}}}))-分区。我们证明,每个周长至少为 5 的平面图都有一个 (F4, F4) 分离。
{"title":"Partitioning planar graph of girth 5 into two forests with maximum degree 4","authors":"Min Chen, André Raspaud, Weifan Wang, Weiqiang Yu","doi":"10.21136/cmj.2024.0394-21","DOIUrl":"https://doi.org/10.21136/cmj.2024.0394-21","url":null,"abstract":"<p>Given a graph <i>G</i> = (<i>V, E</i>), if we can partition the vertex set <i>V</i> into two nonempty subsets <i>V</i><sub>1</sub> and <i>V</i><sub>2</sub> which satisfy Δ(<i>G</i>[<i>V</i><sub>1</sub>]) ⩽ <i>d</i><sub>1</sub> and Δ(<i>G</i>[<i>V</i><sub>2</sub>]) ⩽ <i>d</i><sub>2</sub>, then we say <i>G</i> has a (<span>({{rm{Delta }}_{{d_1}}},,{{rm{Delta }}_{{d_2}}})</span>)-partition. And we say <i>G</i> admits an (<span>({F_{d_{1}}}, {F_{d_{2}}})</span>)-partition if <i>G</i>[<i>V</i><sub>1</sub>] and <i>G</i>[<i>V</i><sub>2</sub>] are both forests whose maximum degree is at most <i>d</i><sub>1</sub> and <i>d</i><sub>2</sub>, respectively. We show that every planar graph with girth at least 5 has an (<i>F</i><sub>4</sub>, <i>F</i><sub>4</sub>)-partition.</p>","PeriodicalId":50596,"journal":{"name":"Czechoslovak Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141501951","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}
Pub Date : 2024-05-16DOI: 10.21136/cmj.2024.0459-23
Liuying Wu
{"title":"On the least almost-prime in arithmetic progressions","authors":"Liuying Wu","doi":"10.21136/cmj.2024.0459-23","DOIUrl":"https://doi.org/10.21136/cmj.2024.0459-23","url":null,"abstract":"","PeriodicalId":50596,"journal":{"name":"Czechoslovak Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140971367","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}
Pub Date : 2024-05-06DOI: 10.21136/cmj.2024.0008-24
Xiaosong Sun, Beini Wang
{"title":"Images of locally nilpotent derivations of bivariate polynomial algebras over a domain","authors":"Xiaosong Sun, Beini Wang","doi":"10.21136/cmj.2024.0008-24","DOIUrl":"https://doi.org/10.21136/cmj.2024.0008-24","url":null,"abstract":"","PeriodicalId":50596,"journal":{"name":"Czechoslovak Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141010171","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}
Pub Date : 2024-04-29DOI: 10.21136/cmj.2024.0065-24
David G. Costanzo, Mark L. Lewis, Stefano Schmidt, Eyob Tsegaye, Gabe Udell
Let G be a finite group and construct a graph Δ(G) by taking G {1} as the vertex set of Δ(G) and by drawing an edge between two vertices x and y if 〈x, y〉 is cyclic. Let K(G) be the set consisting of the universal vertices of Δ(G) along the identity element. For a solvable group G, we present a necessary and sufficient condition for K(G) to be nontrivial. We also develop a connection between Δ(G) and K(G) when ∣G∣ is divisible by two distinct primes and the diameter of Δ(G) is 2.
设 G 是一个有限群,以 G {1} 作为 Δ(G) 的顶点集,并在〈x, y〉循环时在两个顶点 x 和 y 之间画一条边,从而构造一个图 Δ(G)。设 K(G) 是由Δ(G) 沿同一元素的普遍顶点组成的集合。对于可解群 G,我们提出了 K(G) 是非微观的必要条件和充分条件。当 ∣G∣ 被两个不同的素数整除且 Δ(G) 的直径为 2 时,我们还发展了 Δ(G) 与 K(G) 之间的联系。
{"title":"Characterizing finite groups whose enhanced power graphs have universal vertices","authors":"David G. Costanzo, Mark L. Lewis, Stefano Schmidt, Eyob Tsegaye, Gabe Udell","doi":"10.21136/cmj.2024.0065-24","DOIUrl":"https://doi.org/10.21136/cmj.2024.0065-24","url":null,"abstract":"<p>Let <i>G</i> be a finite group and construct a graph Δ(<i>G</i>) by taking <i>G</i> {1} as the vertex set of Δ(<i>G</i>) and by drawing an edge between two vertices <i>x</i> and <i>y</i> if 〈<i>x</i>, <i>y</i>〉 is cyclic. Let <i>K</i>(<i>G</i>) be the set consisting of the universal vertices of Δ(<i>G</i>) along the identity element. For a solvable group <i>G</i>, we present a necessary and sufficient condition for <i>K</i>(<i>G</i>) to be nontrivial. We also develop a connection between Δ(<i>G</i>) and <i>K</i>(<i>G</i>) when ∣<i>G</i>∣ is divisible by two distinct primes and the diameter of Δ(<i>G</i>) is 2.</p>","PeriodicalId":50596,"journal":{"name":"Czechoslovak Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141525284","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}
Pub Date : 2024-04-29DOI: 10.21136/cmj.2024.0038-24
Youjun Wang
Let j ⩾ 2 be a given integer. Let Hk* be the set of all normalized primitive holomorphic cusp forms of even integral weight k ⩾ 2 for the full modulo group SL(2, ℤ). For f ∈ Hk*, denote by ({{rm{lambda }}_{{rm{sy}}{{rm{m}}^j}{kern 1pt} f}}(n)) the nth normalized Fourier coefficient of jth symmetric power L-function (L(s, symjf)) attached to f. We are interested in the average behaviour of the sum
$$sumlimits_{scriptstyle n, = ,a_1^2 + a_2^2 + a_3^2 + a_4^2 + a_5^2 + a_6^2x atop scriptstyle ,,,,,,,({a_1},{a_2},{a_3},{a_4},{a_5},{a_6}{rm{)}} in ,{{mathbb{Z}}^6}} {{rm{lambda }}_{{rm{sy}}{{rm{m}}^j},fleft( n right),}^2}$$
where x is sufficiently large, which improves the recent work of A. Sharma and A. Sankaranarayanan (2023).
设 j ⩾ 2 为给定整数。让 Hk* 是全模态群 SL(2, ℤ)的偶数积分权重 k ⩾ 2 的所有归一化原始全形顶点形式的集合。对于 f∈ Hk*,用 ({{rm{lambda }}_{{rm{sy}}{{rm{m}}^j}{kern 1pt}} f}}(n)) 表示连接到 f 的第 j 个对称幂 L 函数 (L(s, symjf)) 的第 n 个归一化傅里叶系数。我们感兴趣的是总和 $$sumlimits_{scriptstyle n, = 、a_1^2 + a_2^2 + a_3^2 + a_4^2 + a_5^2 + a_6^2x atop scriptstyle ,,,({a_1},{a_2},{a_3},{a_4},{a_5},{a_6}{rm{)}}。in,{{mathbb{Z}}^6}}{{rm{lambda }}_{{rm{sy}}{{rm{m}}^j}},fleft( n right),}^2}$$ 其中 x 足够大,这改进了 A. Sharma 和 A. Sankaranarayanan (2023) 最近的工作。
{"title":"A note on average behaviour of the Fourier coefficients of jth symmetric power L-function over certain sparse sequence of positive integers","authors":"Youjun Wang","doi":"10.21136/cmj.2024.0038-24","DOIUrl":"https://doi.org/10.21136/cmj.2024.0038-24","url":null,"abstract":"<p>Let <i>j</i> ⩾ 2 be a given integer. Let <i>H</i><sub><i>k</i></sub>* be the set of all normalized primitive holomorphic cusp forms of even integral weight <i>k</i> ⩾ 2 for the full modulo group SL(2, ℤ). For <i>f</i> ∈ <i>H</i><sub><i>k</i></sub>*, denote by <span>({{rm{lambda }}_{{rm{sy}}{{rm{m}}^j}{kern 1pt} f}}(n))</span> the <i>n</i>th normalized Fourier coefficient of <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>)) attached to <i>f</i>. We are interested in the average behaviour of the sum </p><span>$$sumlimits_{scriptstyle n, = ,a_1^2 + a_2^2 + a_3^2 + a_4^2 + a_5^2 + a_6^2x atop scriptstyle ,,,,,,,({a_1},{a_2},{a_3},{a_4},{a_5},{a_6}{rm{)}} in ,{{mathbb{Z}}^6}} {{rm{lambda }}_{{rm{sy}}{{rm{m}}^j},fleft( n right),}^2}$$</span><p> where <i>x</i> is sufficiently large, which improves the recent work of A. Sharma and A. Sankaranarayanan (2023).</p>","PeriodicalId":50596,"journal":{"name":"Czechoslovak Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141525283","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}
Pub Date : 2024-04-15DOI: 10.21136/cmj.2024.0356-23
Mahesh Kumar Ram
{"title":"Class groups of large ranks in biquadratic fields","authors":"Mahesh Kumar Ram","doi":"10.21136/cmj.2024.0356-23","DOIUrl":"https://doi.org/10.21136/cmj.2024.0356-23","url":null,"abstract":"","PeriodicalId":50596,"journal":{"name":"Czechoslovak Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140701317","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}
Pub Date : 2024-04-09DOI: 10.21136/cmj.2024.0460-23
Mohammad Ashraf, Mohammad Aslam Siddeeque, Abbas Hussain Shikeh
{"title":"On the characterization of certain additive maps in prime $ast$-rings","authors":"Mohammad Ashraf, Mohammad Aslam Siddeeque, Abbas Hussain Shikeh","doi":"10.21136/cmj.2024.0460-23","DOIUrl":"https://doi.org/10.21136/cmj.2024.0460-23","url":null,"abstract":"","PeriodicalId":50596,"journal":{"name":"Czechoslovak Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140726679","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}