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  Subjects -> MATHEMATICS (Total: 955 journals)
    - APPLIED MATHEMATICS (82 journals)
    - GEOMETRY AND TOPOLOGY (20 journals)
    - MATHEMATICS (706 journals)
    - MATHEMATICS (GENERAL) (43 journals)
    - NUMERICAL ANALYSIS (22 journals)
    - PROBABILITIES AND MATH STATISTICS (82 journals)

MATHEMATICS (706 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 538 Journals sorted alphabetically
Abakós     Open Access   (Followers: 4)
Abhandlungen aus dem Mathematischen Seminar der Universitat Hamburg     Hybrid Journal   (Followers: 3)
Academic Voices : A Multidisciplinary Journal     Open Access   (Followers: 2)
Accounting Perspectives     Full-text available via subscription   (Followers: 7)
ACM Transactions on Algorithms (TALG)     Hybrid Journal   (Followers: 15)
ACM Transactions on Computational Logic (TOCL)     Hybrid Journal   (Followers: 3)
ACM Transactions on Mathematical Software (TOMS)     Hybrid Journal   (Followers: 6)
ACS Applied Materials & Interfaces     Full-text available via subscription   (Followers: 27)
Acta Applicandae Mathematicae     Hybrid Journal   (Followers: 1)
Acta Mathematica     Hybrid Journal   (Followers: 11)
Acta Mathematica Hungarica     Hybrid Journal   (Followers: 2)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5)
Acta Mathematica Sinica, English Series     Hybrid Journal   (Followers: 6)
Acta Mathematica Vietnamica     Hybrid Journal  
Acta Mathematicae Applicatae Sinica, English Series     Hybrid Journal  
Advanced Science Letters     Full-text available via subscription   (Followers: 9)
Advances in Applied Clifford Algebras     Hybrid Journal   (Followers: 3)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 6)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 18)
Advances in Decision Sciences     Open Access   (Followers: 3)
Advances in Difference Equations     Open Access   (Followers: 3)
Advances in Fixed Point Theory     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 13)
Advances in Linear Algebra & Matrix Theory     Open Access   (Followers: 2)
Advances in Materials Sciences     Open Access   (Followers: 14)
Advances in Mathematical Physics     Open Access   (Followers: 3)
Advances in Mathematics     Full-text available via subscription   (Followers: 10)
Advances in Numerical Analysis     Open Access   (Followers: 4)
Advances in Operations Research     Open Access   (Followers: 12)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Pure and Applied Mathematics     Hybrid Journal   (Followers: 6)
Advances in Pure Mathematics     Open Access   (Followers: 5)
Advances in Science and Research (ASR)     Open Access   (Followers: 4)
Aequationes Mathematicae     Hybrid Journal   (Followers: 2)
African Journal of Educational Studies in Mathematics and Sciences     Full-text available via subscription   (Followers: 5)
African Journal of Mathematics and Computer Science Research     Open Access   (Followers: 4)
Afrika Matematika     Hybrid Journal   (Followers: 1)
Air, Soil & Water Research     Open Access   (Followers: 11)
AKSIOMA Journal of Mathematics Education     Open Access   (Followers: 1)
Al-Jabar : Jurnal Pendidikan Matematika     Open Access  
Algebra and Logic     Hybrid Journal   (Followers: 5)
Algebra Colloquium     Hybrid Journal   (Followers: 4)
Algebra Universalis     Hybrid Journal   (Followers: 2)
Algorithmic Operations Research     Full-text available via subscription   (Followers: 5)
Algorithms     Open Access   (Followers: 11)
Algorithms Research     Open Access   (Followers: 1)
American Journal of Computational and Applied Mathematics     Open Access   (Followers: 5)
American Journal of Mathematical Analysis     Open Access  
American Journal of Mathematics     Full-text available via subscription   (Followers: 6)
American Journal of Operations Research     Open Access   (Followers: 5)
American Mathematical Monthly     Full-text available via subscription   (Followers: 6)
An International Journal of Optimization and Control: Theories & Applications     Open Access   (Followers: 8)
Analele Universitatii Ovidius Constanta - Seria Matematica     Open Access   (Followers: 1)
Analysis     Hybrid Journal   (Followers: 2)
Analysis and Applications     Hybrid Journal   (Followers: 1)
Analysis and Mathematical Physics     Hybrid Journal   (Followers: 4)
Analysis Mathematica     Full-text available via subscription  
Annales Mathematicae Silesianae     Open Access  
Annales mathématiques du Québec     Hybrid Journal   (Followers: 4)
Annales UMCS, Mathematica     Open Access   (Followers: 1)
Annales Universitatis Paedagogicae Cracoviensis. Studia Mathematica     Open Access  
Annali di Matematica Pura ed Applicata     Hybrid Journal   (Followers: 1)
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Data Science     Hybrid Journal   (Followers: 11)
Annals of Discrete Mathematics     Full-text available via subscription   (Followers: 6)
Annals of Mathematics     Full-text available via subscription  
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 12)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of the Alexandru Ioan Cuza University - Mathematics     Open Access  
Annals of the Institute of Statistical Mathematics     Hybrid Journal   (Followers: 1)
Annals of West University of Timisoara - Mathematics     Open Access  
Annuaire du Collège de France     Open Access   (Followers: 5)
ANZIAM Journal     Open Access   (Followers: 1)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applications of Mathematics     Hybrid Journal   (Followers: 1)
Applied Categorical Structures     Hybrid Journal   (Followers: 2)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 11)
Applied Mathematics     Open Access   (Followers: 3)
Applied Mathematics     Open Access   (Followers: 6)
Applied Mathematics & Optimization     Hybrid Journal   (Followers: 6)
Applied Mathematics - A Journal of Chinese Universities     Hybrid Journal  
Applied Mathematics Letters     Full-text available via subscription   (Followers: 1)
Applied Mathematics Research eXpress     Hybrid Journal   (Followers: 1)
Applied Network Science     Open Access   (Followers: 3)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arab Journal of Mathematical Sciences     Open Access   (Followers: 3)
Arabian Journal of Mathematics     Open Access   (Followers: 2)
Archive for Mathematical Logic     Hybrid Journal   (Followers: 2)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 5)
Archive of Numerical Software     Open Access  
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 5)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
Armenian Journal of Mathematics     Open Access  
Arnold Mathematical Journal     Hybrid Journal   (Followers: 1)
Artificial Satellites : The Journal of Space Research Centre of Polish Academy of Sciences     Open Access   (Followers: 20)
Asia-Pacific Journal of Operational Research     Hybrid Journal   (Followers: 3)
Asian Journal of Algebra     Open Access   (Followers: 1)
Asian Journal of Current Engineering & Maths     Open Access  
Asian-European Journal of Mathematics     Hybrid Journal   (Followers: 2)
Australian Mathematics Teacher, The     Full-text available via subscription   (Followers: 6)
Australian Primary Mathematics Classroom     Full-text available via subscription   (Followers: 4)
Australian Senior Mathematics Journal     Full-text available via subscription   (Followers: 1)
Automatic Documentation and Mathematical Linguistics     Hybrid Journal   (Followers: 5)
Axioms     Open Access   (Followers: 1)
Baltic International Yearbook of Cognition, Logic and Communication     Open Access   (Followers: 1)
Basin Research     Hybrid Journal   (Followers: 5)
BIBECHANA     Open Access   (Followers: 2)
BIT Numerical Mathematics     Hybrid Journal  
BoEM - Boletim online de Educação Matemática     Open Access  
Boletim Cearense de Educação e História da Matemática     Open Access  
Boletim de Educação Matemática     Open Access  
Boletín de la Sociedad Matemática Mexicana     Hybrid Journal  
Bollettino dell'Unione Matematica Italiana     Full-text available via subscription   (Followers: 1)
British Journal of Mathematical and Statistical Psychology     Full-text available via subscription   (Followers: 21)
Bruno Pini Mathematical Analysis Seminar     Open Access  
Buletinul Academiei de Stiinte a Republicii Moldova. Matematica     Open Access   (Followers: 11)
Bulletin des Sciences Mathamatiques     Full-text available via subscription   (Followers: 4)
Bulletin of Dnipropetrovsk University. Series : Communications in Mathematical Modeling and Differential Equations Theory     Open Access   (Followers: 1)
Bulletin of Mathematical Sciences     Open Access   (Followers: 1)
Bulletin of Symbolic Logic     Full-text available via subscription   (Followers: 2)
Bulletin of the Australian Mathematical Society     Full-text available via subscription   (Followers: 1)
Bulletin of the Brazilian Mathematical Society, New Series     Hybrid Journal  
Bulletin of the London Mathematical Society     Hybrid Journal   (Followers: 4)
Bulletin of the Malaysian Mathematical Sciences Society     Hybrid Journal  
Calculus of Variations and Partial Differential Equations     Hybrid Journal  
Canadian Journal of Science, Mathematics and Technology Education     Hybrid Journal   (Followers: 18)
Carpathian Mathematical Publications     Open Access   (Followers: 1)
Catalysis in Industry     Hybrid Journal   (Followers: 1)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
CHANCE     Hybrid Journal   (Followers: 5)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
ChemSusChem     Hybrid Journal   (Followers: 7)
Chinese Annals of Mathematics, Series B     Hybrid Journal  
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Mathematics     Open Access  
Clean Air Journal     Full-text available via subscription   (Followers: 1)
Cogent Mathematics     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Collectanea Mathematica     Hybrid Journal  
College Mathematics Journal     Full-text available via subscription   (Followers: 4)
COMBINATORICA     Hybrid Journal  
Combinatorics, Probability and Computing     Hybrid Journal   (Followers: 4)
Combustion Theory and Modelling     Hybrid Journal   (Followers: 14)
Commentarii Mathematici Helvetici     Hybrid Journal   (Followers: 1)
Communications in Combinatorics and Optimization     Open Access  
Communications in Contemporary Mathematics     Hybrid Journal  
Communications in Mathematical Physics     Hybrid Journal   (Followers: 2)
Communications On Pure & Applied Mathematics     Hybrid Journal   (Followers: 3)
Complex Analysis and its Synergies     Open Access   (Followers: 2)
Complex Variables and Elliptic Equations: An International Journal     Hybrid Journal  
Complexus     Full-text available via subscription  
Composite Materials Series     Full-text available via subscription   (Followers: 8)
Compositio Mathematica     Full-text available via subscription   (Followers: 1)
Comptes Rendus Mathematique     Full-text available via subscription   (Followers: 1)
Computational and Applied Mathematics     Hybrid Journal   (Followers: 2)
Computational and Mathematical Methods in Medicine     Open Access   (Followers: 2)
Computational and Mathematical Organization Theory     Hybrid Journal   (Followers: 2)
Computational Complexity     Hybrid Journal   (Followers: 4)
Computational Mathematics and Modeling     Hybrid Journal   (Followers: 8)
Computational Mechanics     Hybrid Journal   (Followers: 5)
Computational Methods and Function Theory     Hybrid Journal  
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 8)
Concrete Operators     Open Access   (Followers: 5)
Confluentes Mathematici     Hybrid Journal  
Contributions to Game Theory and Management     Open Access  
COSMOS     Hybrid Journal  
Cryptography and Communications     Hybrid Journal   (Followers: 12)
Cuadernos de Investigación y Formación en Educación Matemática     Open Access  
Cubo. A Mathematical Journal     Open Access  
Current Research in Biostatistics     Open Access   (Followers: 9)
Czechoslovak Mathematical Journal     Hybrid Journal   (Followers: 1)
Demographic Research     Open Access   (Followers: 10)
Demonstratio Mathematica     Open Access  
Dependence Modeling     Open Access  
Design Journal : An International Journal for All Aspects of Design     Hybrid Journal   (Followers: 29)
Developments in Clay Science     Full-text available via subscription   (Followers: 1)
Developments in Mineral Processing     Full-text available via subscription   (Followers: 3)
Dhaka University Journal of Science     Open Access  
Differential Equations and Dynamical Systems     Hybrid Journal   (Followers: 3)
Differentsial'nye Uravneniya     Open Access  
Discrete Mathematics     Hybrid Journal   (Followers: 8)
Discrete Mathematics & Theoretical Computer Science     Open Access  
Discrete Mathematics, Algorithms and Applications     Hybrid Journal   (Followers: 2)
Discussiones Mathematicae - General Algebra and Applications     Open Access  
Discussiones Mathematicae Graph Theory     Open Access   (Followers: 1)
Diskretnaya Matematika     Full-text available via subscription  
Dnipropetrovsk University Mathematics Bulletin     Open Access  
Doklady Akademii Nauk     Open Access  
Doklady Mathematics     Hybrid Journal  
Duke Mathematical Journal     Full-text available via subscription   (Followers: 1)
Eco Matemático     Open Access  
Edited Series on Advances in Nonlinear Science and Complexity     Full-text available via subscription  
Electronic Journal of Differential Equations     Open Access  
Electronic Journal of Graph Theory and Applications     Open Access   (Followers: 2)
Electronic Notes in Discrete Mathematics     Full-text available via subscription   (Followers: 2)
Elemente der Mathematik     Full-text available via subscription   (Followers: 4)

        1 2 3 4 | Last

Journal Cover Acta Mathematica Hungarica
  [SJR: 0.53]   [H-I: 29]   [2 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1588-2632 - ISSN (Online) 0236-5294
   Published by Springer-Verlag Homepage  [2352 journals]
  • Local derivations of finitary incidence algebras
    • Authors: M. Khrypchenko
      Pages: 48 - 55
      Abstract: Let P be a partially ordered set, R a commutative ring with identity and FI(P,R) the finitary incidence algebra of P over R. We prove that each R-linear local derivation of FI(P,R) is a derivation, which partially generalizes Theorem 3 of [21].
      PubDate: 2018-02-01
      DOI: 10.1007/s10474-017-0758-7
      Issue No: Vol. 154, No. 1 (2018)
       
  • Marcinkiewicz–Zygmund type results in multivariate domains
    • Authors: S. De Marchi; A. Kroó
      Pages: 69 - 89
      Abstract: We investigate Marcinkiewicz–Zygmund type inequalities for multivariate polynomials on various compact domains in \({\mathbb{R}^d}\) . These inequalities provide a basic tool for the discretization of the L p norm and are widely used in the study of the convergence properties of Fourier series, interpolation processes and orthogonal expansions. Recently Marcinkiewicz–Zygmund type inequalities were verified for univariate polynomials for the general class of doubling weights, and for multivariate polynomials on the ball and sphere with doubling weights. The main goal of the present paper is to extend these considerations to more general multidimensional domains, which in particular include polytopes, cones, spherical sectors, toruses, etc. Our approach will rely on application of various polynomial inequalities, such as Bernstein–Markov, Schur and Videnskii type estimates, and also using symmetry and rotation in order to generate results on new domains.
      PubDate: 2018-02-01
      DOI: 10.1007/s10474-017-0769-4
      Issue No: Vol. 154, No. 1 (2018)
       
  • Metric Mahler measures over number fields
    • Authors: C. L. Samuels
      Pages: 105 - 123
      Abstract: For an algebraic number α, the metric Mahler measure \({m_1(\alpha)}\) was first studied by Dubickas and Smyth [4] and was later generalized to the t-metric Mahler measure \({m_t(\alpha)}\) by the author [16]. The definition of \({m_t(\alpha)}\) involves taking an infimum over a certain collection N-tuples of points in \(\overline{\mathbb{Q}}\) , and from previous work of Jankauskas and the author, the infimum in the definition of \({m_t(\alpha)}\) is attained by rational points when \({\alpha\in \mathbb{Q}}\) . As a consequence of our main theorem in this article, we obtain an analog of this result when \({\mathbb{Q}}\) is replaced with any imaginary quadratic number field of class number equal to 1. Further, we study examples of other number fields to which our methods may be applied, and we establish various partial results in those cases.
      PubDate: 2018-02-01
      DOI: 10.1007/s10474-017-0770-y
      Issue No: Vol. 154, No. 1 (2018)
       
  • Unions of left-separated spaces
    • Authors: E. Scheidecker; A. Stanley
      Pages: 124 - 133
      Abstract: A space is left-separated if it has a well ordering for which initial segments are closed. We explore when the union of two left-separated spaces must be left-separated. We prove that if X and Y are left-separated and \({X \cup Y}\) is locally countable, then whenever \({{\rm ord}_\ell(Y ) \leq \omega_{1}, X \cup Y}\) is left-separated. In 1986, Fleissner [2] proved that if a space has a point-countable base, then it is left-separated if and only if it is \({\sigma}\) -weakly separated. We provide a new proof of this result using elementary submodels and add an additional characterization.
      PubDate: 2018-02-01
      DOI: 10.1007/s10474-017-0771-x
      Issue No: Vol. 154, No. 1 (2018)
       
  • On hypergeometric Bernoulli numbers and polynomials
    • Authors: S. Hu; M.-S. Kim
      Pages: 134 - 146
      Abstract: We provide several properties of hypergeometric Bernoulli numbers and polynomials, including sums of products identity, differential equations and recurrence formulas.
      PubDate: 2018-02-01
      DOI: 10.1007/s10474-017-0767-6
      Issue No: Vol. 154, No. 1 (2018)
       
  • On the connectivity of infinite graphs
    • Authors: P. Komjáth
      Pages: 215 - 222
      Abstract: Let \({\mu \geq \omega}\) be regular, assume the Generalized Continuum Hypothesis and the principle \({\square_\lambda}\) holds for every singular \({\lambda}\) with \({{\rm cf}(\lambda) \leq \mu}\) . Let X be a graph with chromatic number greater than \({\mu^+}\) . Then X contains a \({\mu}\) -connected subgraph Y of X whose chromatic number is greater than \({\mu^+}\) .
      PubDate: 2018-02-01
      DOI: 10.1007/s10474-017-0752-0
      Issue No: Vol. 154, No. 1 (2018)
       
  • Note on the Hochschild cohomology of Hopf–Galois extension
    • Authors: Z. Wang
      Pages: 223 - 230
      Abstract: We generalize [4, Theorem 4.3] to the case of Hopf–Galois extension, by introducing the cotensor product of a comodule algebra and its opposite algebra, and then give some applications.
      PubDate: 2018-02-01
      DOI: 10.1007/s10474-017-0765-8
      Issue No: Vol. 154, No. 1 (2018)
       
  • Fodor’s lemma can fail everywhere
    • Authors: A. Karagila
      Pages: 231 - 242
      Abstract: We show that it is equiconsistent with \({\mathsf{ZF}}\) that Fodor’s lemma fails everywhere, and furthermore that the club filter on every regular cardinal is not even \({\sigma}\) -complete. Moreover, these failures can be controlled in a very precise manner.
      PubDate: 2018-02-01
      DOI: 10.1007/s10474-017-0768-5
      Issue No: Vol. 154, No. 1 (2018)
       
  • On patterns of conditional independences and covariance signs among binary
           variables
    • Authors: F. Matúš
      Abstract: Given finitely many events in a probability space, conditional independences among the indicators of events are considered simultaneously with the signs of covariances. Resulting discrete structures are studied restricting attention mostly to all couples and triples of events. Necessary and sufficient conditions for such structures to be represented by events are found. Consequences of the results for the patterns of conjunctive forks are discussed.
      PubDate: 2018-02-22
      DOI: 10.1007/s10474-018-0799-6
       
  • Kernel ideals and cokernel filters of a p-algebra
    • Authors: S. N. Begum; C. Nag; M. R. Talukder
      Abstract: We discuss congruences of p-algebras. We characterize kernel ideals of a p-algebra. Indeed, we show that an ideal of a p-algebra is a p-ideal if and only if it is a kernel ideal. We study cokernel filters of a p-algebra. We construct a class of p-algebras in which every cokernel filter is a p-filter. We also give some characterizations of Boolean congruences of a p-algebra.
      PubDate: 2018-02-22
      DOI: 10.1007/s10474-018-0793-z
       
  • Discriminants of polynomials in the Archimedean and non-Archimedean
           metrics
    • Authors: V. Bernik; N. Budarina; H. O’Donnell
      Abstract: An upper bound for the number of cubic polynomials which have small discriminant in terms of the Euclidean and p-adic metrics simultaneously is obtained.
      PubDate: 2018-02-22
      DOI: 10.1007/s10474-018-0794-y
       
  • An improved upper bound for the size of a sunflower-free family
    • Authors: G. Hegedűs
      Abstract: We combine here Tao’s slice-rank bounding method and Gröbner basis techniques and apply it to the Erdős–Rado Sunflower Conjecture. Let \({0\leq k\leq n}\) be integers. We prove that if \({\mathcal{F}}\) is a k-uniform family of subsets of [n] without a sunflower with 3 petals, then $$ \mathcal{F} \leq3 \left(\begin{array}{c} {n }\\ \lfloor n/3\rfloor \end{array}\right).$$ This result allows us to improve slightly a recent upper bound of Naslund and Sawin for the size of a sunflower-free family in 2[n].
      PubDate: 2018-02-22
      DOI: 10.1007/s10474-018-0798-7
       
  • Application of selection principles in the study of the properties of
           function spaces
    • Authors: A. V. Osipov
      Abstract: For a Tychonoff space X, we denote by C p (X) the space of all real-valued continuous functions on X with the topology of pointwise convergence. In this paper we prove that: If every finite power of X is Lindelöf then C p (X) is strongly sequentially separable iff X is \({\gamma}\) -set. \({B_{\alpha}(X)}\) (= functions of Baire class \({\alpha}\) ( \({1 < \alpha \leq \omega_1}\) ) on a Tychonoff space X with the pointwise topology) is sequentially separable iff there exists a Baire isomorphism class \({\alpha}\) from a space X onto a \({\sigma}\) -set. \({B_{\alpha}(X)}\) is strongly sequentially separable iff \({iw(X)=\aleph_0}\) and X is a \({Z^{\alpha}}\) -cover \({\gamma}\) -set for \({0 < \alpha \leq \omega_1}\) . There is a consistent example of a set of reals X such that C p (X) is strongly sequentially separable but B1(X) is not strongly sequentially separable. B(X) is sequentially separable but is not strongly sequentially separable for a \({\mathfrak{b}}\) -Sierpiński set X.
      PubDate: 2018-02-22
      DOI: 10.1007/s10474-018-0800-4
       
  • On the structure of a mutually permutable product of finite groups
    • Authors: J. Cossey; Y.-M. Li
      Abstract: Let a finite group \({G = AB}\) be the product of the mutually permutable subgroups A and B. We investigate the structure of G given by conditions on conjugacy class sizes of elements in \({A \cup B}\) . Some recent results are extended.
      PubDate: 2018-02-22
      DOI: 10.1007/s10474-018-0796-9
       
  • Conditional equations for quadratic functions
    • Authors: Z. Boros; E. Garda-Mátyás
      Abstract: We consider quadratic functions f that satisfy the additional equation y2 f(x) =  x2 f(y) for the pairs \({ (x,y) \in \mathbb{R}^2}\) that fulfill the condition P(x, y) =  0 for some fixed polynomial P of two variables. If P(x, y) =  ax +  by +  c with \({ a , b , c \in \mathbb{R}}\) and \({(a^2 + b^2)c \neq 0}\) or P(x,y) =  x n − y with a natural number \({n \geq 2}\) , we prove that f(x) =  f(1) x2 for all \({x \in \mathbb{R}}\) . Some related problems, admitting quadratic functions generated by derivations, are considered as well.
      PubDate: 2018-02-22
      DOI: 10.1007/s10474-018-0795-x
       
  • Centralizing traces with automorphisms on triangular algebras
    • Authors: A. Fošner; X.-F. Liang; F. Wei
      Abstract: Let \({\mathcal{T}}\) be a triangular algebra over a commutative ring \({\mathcal{R}}\) , \({\xi}\) be an automorphism of \({\mathcal{T}}\) and \({\mathcal{Z}_{\xi}(\mathcal{T})}\) be the \({\xi}\) -center of \({\mathcal{T}}\) . Suppose that \({\mathfrak{q} \colon \mathcal{T} \times \mathcal{T} \longrightarrow \mathcal{T}}\) is an \({\mathcal{R}}\) -bilinear mapping and that \({\mathfrak{T}_{\mathfrak{q}} \colon \mathcal{T} \longrightarrow \mathcal{T}}\) is a trace of \({\mathfrak{q}}\) . The aim of this article is to describe the form of \({\mathfrak{T}_{\mathfrak{q}}}\) satisfying the commuting condition \({[\mathfrak{T}_{\mathfrak{q}}(x), x]_{\xi}=0}\) (resp. the centralizing condition \({[\mathfrak{T}_{\mathfrak{q}}(x), x]_{\xi} \in \mathcal{Z}_\xi(\mathcal{T})}\) ) for all \({x\in \mathcal{T}}\) . More precisely, we will consider the question of when \({\mathfrak{T}_{\mathfrak{q}}}\) satisfying the previous condition has the so-called proper form.
      PubDate: 2018-02-22
      DOI: 10.1007/s10474-018-0797-8
       
  • On the stability of a generalization of Jensen functional equation
    • Authors: M. Almahalebi
      Abstract: Using the fixed point method, we investigate the stability of a generalization of Jensen functional equation $$ \sum_{k=0}^{n-1} f(x+ b_{k}y)=nf(x),$$ where \({n \in \mathbb{N}_{2}}\) , \({b_{k}=\exp(\frac{2i\pi k}{n})}\) for \({0\leq k \leq n-1}\) , in Banach spaces. Also, we prove the hyperstability results of this equation by the fixed point method.
      PubDate: 2017-12-15
      DOI: 10.1007/s10474-017-0781-8
       
  • Preserved under Sacks forcing again'
    • Authors: Y. Y. Zheng
      Abstract: A hierarchy of topological Ramsey spaces \({\mathcal{R}_\alpha}\) ( \({\alpha < \omega_1}\) ), generalizing the Ellentuck space, were built by Dobrinen and Todorcevic in order to completely classify certain equivalent classes of ultrafilters Tukey (resp. Rudin–Keisler) below \({\mathcal{U}_\alpha}\) \({(\alpha < \omega_1)}\) , where \({\mathcal{U}_\alpha}\) are ultrafilters constructed by Laflamme satisfying certain partition properties and have complete combinatorics over the Solovay model. We show that Nash–Williams, or Ramsey ultrafilters in these spaces are preserved under countable-support side-by-side Sacks forcing. This is achieved by proving a parametrized theorem for these spaces, and showing that Nash–Williams ultrafilters localizes the theorem. We also show that every Nash–Williams ultrafilter in \({\mathcal{R}_\alpha}\) is selective.
      PubDate: 2017-12-14
      DOI: 10.1007/s10474-017-0780-9
       
  • Approximation orders of the unit in the β -dynamical systems
    • Authors: C.-Y. Cao; Y.-H. Chen
      Abstract: For any real number β > 1, let S n (β) be the partial sum of the first n items of the β-expansion of 1. It was known that the approximation order of 1 by S n (β) is β −n for Lebesgue almost all β > 1. We consider the size of the set of β > 1 for which 1 can be approximated with the other orders \({\beta^{-\varphi(n)}}\) , where \({\varphi}\) is a positive function defined on \({\mathbb N}\) . More precisely, the size of the sets $$\left\{\beta\in \mathfrak{B}:\limsup_{n\rightarrow\infty}\frac{\log_{\beta}(1-S_n(\beta))}{\varphi(n)}=-1\right\}$$ and $$\left\{\beta\in \mathfrak{B}:\liminf_{n\rightarrow\infty}\frac{\log_{\beta}(1-S_n(\beta))}{\varphi(n)}=-1\right\}$$ are determined, where \({\mathfrak{B}=\{ \beta>1:\beta \text{ is not a simple Parry number}\}}\) .
      PubDate: 2017-12-14
      DOI: 10.1007/s10474-017-0776-5
       
  • On the generalization of the Salem test
    • Authors: T. Akhobadze; Sh. Zviadadze
      Abstract: The assertion that the Salem test [5] for the uniform convergence of a trigonometric Fourier series is improvable, is proved. In particular, an example of a continuous function, which does not fulfill the condition of the Salem test but satisfies the condition of the generalized Salem test [10], is constructed. Besides, the theorem which improves Golubov’s [3,4] result for continuous functions of two variables, is given.
      PubDate: 2017-12-14
      DOI: 10.1007/s10474-017-0774-7
       
 
 
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