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Lucas numbers of the form (2t/k) 形式为(2t/k)的卢卡斯数
IF 0.3
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2019-08-09 DOI: 10.12697/ACUTM.2019.23.06
N. Irmak, L. Szalay
{"title":"Lucas numbers of the form (2t/k)","authors":"N. Irmak, L. Szalay","doi":"10.12697/ACUTM.2019.23.06","DOIUrl":"https://doi.org/10.12697/ACUTM.2019.23.06","url":null,"abstract":"Let Lm denote the mth Lucas number. We show that the solutions to the diophantine equation (2t/k) = Lm, in non-negative integers t, k ≤ 2t−1, and m, are (t, k, m) = (1, 1, 0), (2, 1, 3), and (a, 0, 1) with non-negative integers a.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"144 1 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80999694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Pseudo-symmetric structures on almost Kenmotsu manifolds with nullity distributions 具有零分布的几乎Kenmotsu流形上的伪对称结构
IF 0.3
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2019-08-09 DOI: 10.12697/ACUTM.2019.23.02
U. De, D. Dey
{"title":"Pseudo-symmetric structures on almost Kenmotsu manifolds with nullity distributions","authors":"U. De, D. Dey","doi":"10.12697/ACUTM.2019.23.02","DOIUrl":"https://doi.org/10.12697/ACUTM.2019.23.02","url":null,"abstract":"The object of the present paper is to characterize Ricci pseudosymmetric and Ricci semisymmetric almost Kenmotsu manifolds with (k; μ)-, (k; μ)′-, and generalized (k; μ)-nullity distributions. We also characterize (k; μ)-almost Kenmotsu manifolds satisfying the condition R ⋅ S = LꜱQ(g; S2).","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"11 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81527031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 7
Structure and classification of Hom-associative algebras 共轭代数的结构与分类
IF 0.3
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2019-06-12 DOI: 10.12697/ACUTM.2020.24.06
A. Makhlouf, Ahmed Zahari
{"title":"Structure and classification of Hom-associative algebras","authors":"A. Makhlouf, Ahmed Zahari","doi":"10.12697/ACUTM.2020.24.06","DOIUrl":"https://doi.org/10.12697/ACUTM.2020.24.06","url":null,"abstract":"The purpose of this paper is to study the structure and the algebraic varieties of Hom-associative algebras. We characterize multiplicative simple Hom-associative algebras and give some examples deforming the 2 × 2-matrix algebra to simple Hom-associative algebras. We provide a classification of n-dimensional Hom-associative algebras for n ≤ 3. Then we study irreducible components using deformation theory.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"57 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84874468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 12
Fekete's lemma for componentwise subadditive functions of two or more real variables 两个或两个以上实变量的分量次加性函数的Fekete引理
IF 0.3
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2019-04-08 DOI: 10.12697/acutm.2022.26.04
Silvio Capobianco
{"title":"Fekete's lemma for componentwise subadditive functions of two or more real variables","authors":"Silvio Capobianco","doi":"10.12697/acutm.2022.26.04","DOIUrl":"https://doi.org/10.12697/acutm.2022.26.04","url":null,"abstract":"We prove an analogue of Fekete's subadditivity lemma for functions of several real variables which are subadditive in each variable taken singularly. This extends both the classical case for subadditive functions of one real variable, and a similar result for functions of integer variables. While doing so, we prove that the functions with the property mentioned above are bounded in every closed and bounded subset of their domain. The arguments expand on those in Chapter 6 of E. Hille's 1948 textbook.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"85 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89704561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
On two integrability methods 关于两种可积性方法
IF 0.3
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2019-01-02 DOI: 10.12697/ACUTM.2018.22.21
H. Özgen
{"title":"On two integrability methods","authors":"H. Özgen","doi":"10.12697/ACUTM.2018.22.21","DOIUrl":"https://doi.org/10.12697/ACUTM.2018.22.21","url":null,"abstract":"<jats:p>See PDF</jats:p>","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"26 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85077326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Inequalities of Hermite–Hadamard type for HH-convex functions hh -凸函数的Hermite-Hadamard型不等式
IF 0.3
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2019-01-02 DOI: 10.12697/ACUTM.2018.22.15
S. Dragomir
{"title":"Inequalities of Hermite–Hadamard type for HH-convex functions","authors":"S. Dragomir","doi":"10.12697/ACUTM.2018.22.15","DOIUrl":"https://doi.org/10.12697/ACUTM.2018.22.15","url":null,"abstract":"Some inequalities of Hermite–Hadamard type for HH-convex functions defined on positive intervals are given. Applications for special means are also provided.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"52 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84737322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
Behaviour of multivariate tail dependence coefficients 多元尾相关系数的行为
IF 0.3
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2019-01-02 DOI: 10.12697/ACUTM.2018.22.25
G. Pettere, I. Voronova, I. Zariņa
{"title":"Behaviour of multivariate tail dependence coefficients","authors":"G. Pettere, I. Voronova, I. Zariņa","doi":"10.12697/ACUTM.2018.22.25","DOIUrl":"https://doi.org/10.12697/ACUTM.2018.22.25","url":null,"abstract":"In applications tail dependence is an important property of a copula. Bivariate tail dependence is investigated in many papers, but multivariate tail dependence has not been studied widely. We define multivariate upper and lower tail dependence coefficients as limits of the probability that values of one marginal will be large if at least one of other marginals will be as large also. Further we derive some relations between introduced tail dependence and bivariate tail dependence coefficients. Applications have shown that the multivariate t-copula has been successfully used in practice because of its tail dependence property. Therefore, t-copula can be used as an alternative method for risk assessment under Solvency II for insurance models. We have paid attention to the properties of the introduced multivariate tail dependence coefficient for t-copula and examine it in the simulation experiment.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"36 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85405462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Simplifying coefficients in a family of nonlinear ordinary differential equations 一类非线性常微分方程的系数化简
IF 0.3
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2019-01-02 DOI: 10.12697/ACUTM.2018.22.24
Feng Qi (祁锋)
{"title":"Simplifying coefficients in a family of nonlinear ordinary differential equations","authors":"Feng Qi (祁锋)","doi":"10.12697/ACUTM.2018.22.24","DOIUrl":"https://doi.org/10.12697/ACUTM.2018.22.24","url":null,"abstract":"By virtue of the Faá di Bruno formula, properties of the Stirling numbers and the Bell polynomials of the second kind, the binomial inversion formula, and other techniques in combinatorial analysis, the author finds a simple, meaningful, and signicant expression for coefficients in a family of nonlinear ordinary differential equations.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"31 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88768580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 8
On concircular curvature tensor in a Lorentzian α-Sasakian manifold with respect to the quarter-symmetric non-metric connection Lorentzian α-Sasakian流形中关于四分之一对称非度量连接的共圆曲率张量
IF 0.3
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2019-01-02 DOI: 10.12697/ACUTM.2018.22.23
A. Haseeb, R. Prasad
{"title":"On concircular curvature tensor in a Lorentzian α-Sasakian manifold with respect to the quarter-symmetric non-metric connection","authors":"A. Haseeb, R. Prasad","doi":"10.12697/ACUTM.2018.22.23","DOIUrl":"https://doi.org/10.12697/ACUTM.2018.22.23","url":null,"abstract":"In the present paper, some properties of concircular curvature tensor in a Lorentzian α-Sasakian manifold with respect to the quarter-symmetric non-metric connection have been studied.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"34 5-8","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72454969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Empirical cumulant function based parameter estimation in stable laws 稳定律中基于经验累积函数的参数估计
IF 0.3
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2019-01-02 DOI: 10.12697/ACUTM.2018.22.26
Annika Krutto
{"title":"Empirical cumulant function based parameter estimation in stable laws","authors":"Annika Krutto","doi":"10.12697/ACUTM.2018.22.26","DOIUrl":"https://doi.org/10.12697/ACUTM.2018.22.26","url":null,"abstract":"Stable distributions are a subclass of infinitely divisible distributions that form the only family of possible limiting distributions for sums of independent identically distributed random variables. A challenging problem is estimating their parameters because many have densities with no explicit form and infinite moments. To address this problem, a class of closed-form estimators, called cumulant estimators, has been introduced. Cumulant estimators are derived from the logarithm of empirical characteristic function at two arbitrary distinct positive real arguments. This paper extends cumulant estimators in two directions: (i) it is proved that they are asymptotically normal and (ii) a sample based rule for selecting the two arguments is proposed. Extensive simulations show that under the provided selection rule, the closed-form cumulant estimators generally outperform the well-known algorithmic methods.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"80 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86623193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
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