Subjects -> MATHEMATICS (Total: 1100 journals)
    - APPLIED MATHEMATICS (88 journals)
    - GEOMETRY AND TOPOLOGY (23 journals)
    - MATHEMATICS (812 journals)
    - MATHEMATICS (GENERAL) (43 journals)
    - NUMERICAL ANALYSIS (24 journals)

MATHEMATICS (812 journals)                  1 2 3 4 5 | Last

Showing 1 - 200 of 538 Journals sorted alphabetically
Abakós     Open Access   (Followers: 5)
Abhandlungen aus dem Mathematischen Seminar der Universitat Hamburg     Hybrid Journal   (Followers: 4)
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: 16)
ACM Transactions on Computational Logic (TOCL)     Hybrid Journal   (Followers: 3)
ACM Transactions on Mathematical Software (TOMS)     Hybrid Journal   (Followers: 6)
ACS Applied Materials & Interfaces     Hybrid Journal   (Followers: 39)
Acta Applicandae Mathematicae     Hybrid Journal   (Followers: 1)
Acta Mathematica     Hybrid Journal   (Followers: 13)
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: 12)
Advances in Applied Clifford Algebras     Hybrid Journal   (Followers: 4)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 6)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 10)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 23)
Advances in Decision Sciences     Open Access   (Followers: 4)
Advances in Difference Equations     Open Access   (Followers: 3)
Advances in Fixed Point Theory     Open Access   (Followers: 8)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 19)
Advances in Linear Algebra & Matrix Theory     Open Access   (Followers: 11)
Advances in Materials Science     Open Access   (Followers: 19)
Advances in Mathematical Physics     Open Access   (Followers: 8)
Advances in Mathematics     Full-text available via subscription   (Followers: 17)
Advances in Nonlinear Analysis     Open Access   (Followers: 1)
Advances in Numerical Analysis     Open Access   (Followers: 9)
Advances in Operations Research     Open Access   (Followers: 13)
Advances in Operator Theory     Hybrid Journal   (Followers: 4)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Pure and Applied Mathematics     Hybrid Journal   (Followers: 10)
Advances in Pure Mathematics     Open Access   (Followers: 11)
Advances in Science and Research (ASR)     Open Access   (Followers: 9)
Aequationes Mathematicae     Hybrid Journal   (Followers: 2)
African Journal of Educational Studies in Mathematics and Sciences     Full-text available via subscription   (Followers: 9)
African Journal of Mathematics and Computer Science Research     Open Access   (Followers: 7)
Afrika Matematika     Hybrid Journal   (Followers: 3)
Air, Soil & Water Research     Open Access   (Followers: 13)
AKSIOMA Journal of Mathematics Education     Open Access   (Followers: 3)
AKSIOMATIK : Jurnal Penelitian Pendidikan dan Pembelajaran Matematika     Open Access   (Followers: 1)
Al-Jabar : Jurnal Pendidikan Matematika     Open Access   (Followers: 1)
Al-Qadisiyah Journal for Computer Science and Mathematics     Open Access   (Followers: 1)
AL-Rafidain Journal of Computer Sciences and Mathematics     Open Access   (Followers: 6)
Algebra and Logic     Hybrid Journal   (Followers: 7)
Algebra Colloquium     Hybrid Journal   (Followers: 4)
Algebra Universalis     Hybrid Journal   (Followers: 2)
Algorithmic Operations Research     Open Access   (Followers: 5)
Algorithms     Open Access   (Followers: 12)
Algorithms Research     Open Access   (Followers: 1)
American Journal of Computational and Applied Mathematics     Open Access   (Followers: 10)
American Journal of Mathematical Analysis     Open Access   (Followers: 2)
American Journal of Mathematical and Management Sciences     Hybrid Journal   (Followers: 1)
American Journal of Mathematics     Full-text available via subscription   (Followers: 7)
American Journal of Operations Research     Open Access   (Followers: 8)
American Mathematical Monthly     Full-text available via subscription   (Followers: 6)
An International Journal of Optimization and Control: Theories & Applications     Open Access   (Followers: 11)
Anadol University Journal of Science and Technology B : Theoritical Sciences     Open Access  
Analele Universitatii Ovidius Constanta - Seria Matematica     Open Access  
Analysis and Applications     Hybrid Journal   (Followers: 1)
Analysis and Mathematical Physics     Hybrid Journal   (Followers: 6)
Analysis Mathematica     Full-text available via subscription  
Analysis. International mathematical journal of analysis and its applications     Hybrid Journal   (Followers: 5)
Anargya : Jurnal Ilmiah Pendidikan Matematika     Open Access   (Followers: 3)
Annales Mathematicae Silesianae     Open Access   (Followers: 2)
Annales mathématiques du Québec     Hybrid Journal   (Followers: 4)
Annales Universitatis Mariae Curie-Sklodowska, sectio A – 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: 4)
Annals of Data Science     Hybrid Journal   (Followers: 13)
Annals of Discrete Mathematics     Full-text available via subscription   (Followers: 8)
Annals of Functional Analysis     Hybrid Journal   (Followers: 4)
Annals of Mathematics     Full-text available via subscription   (Followers: 3)
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 14)
Annals of PDE     Hybrid Journal   (Followers: 1)
Annals of Pure and Applied Logic     Open Access   (Followers: 4)
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  
Annals of West University of Timisoara - Mathematics and Computer Science     Open Access   (Followers: 2)
Annuaire du Collège de France     Open Access   (Followers: 6)
ANZIAM Journal     Open Access   (Followers: 1)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 3)
Applications of Mathematics     Hybrid Journal   (Followers: 3)
Applied Categorical Structures     Hybrid Journal   (Followers: 4)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 14)
Applied Mathematics     Open Access   (Followers: 4)
Applied Mathematics     Open Access   (Followers: 8)
Applied Mathematics & Optimization     Hybrid Journal   (Followers: 10)
Applied Mathematics - A Journal of Chinese Universities     Hybrid Journal   (Followers: 1)
Applied Mathematics and Nonlinear Sciences     Open Access  
Applied Mathematics Letters     Full-text available via subscription   (Followers: 4)
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: 6)
Arab Journal of Mathematical Sciences     Open Access   (Followers: 4)
Arabian Journal of Mathematics     Open Access   (Followers: 2)
Archive for Mathematical Logic     Hybrid Journal   (Followers: 3)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 6)
Archive of Numerical Software     Open Access  
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 6)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
Armenian Journal of Mathematics     Open Access   (Followers: 1)
Arnold Mathematical Journal     Hybrid Journal   (Followers: 1)
Artificial Satellites     Open Access   (Followers: 24)
Asia-Pacific Journal of Operational Research     Hybrid Journal   (Followers: 3)
Asian Journal of Algebra     Open Access   (Followers: 1)
Asian Research Journal of Mathematics     Open Access   (Followers: 1)
Asian-European Journal of Mathematics     Hybrid Journal   (Followers: 3)
Australian Mathematics Teacher, The     Full-text available via subscription   (Followers: 7)
Australian Primary Mathematics Classroom     Full-text available via subscription   (Followers: 5)
Australian Senior Mathematics Journal     Full-text available via subscription   (Followers: 2)
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: 2)
Banach Journal of Mathematical Analysis     Hybrid Journal   (Followers: 2)
Basin Research     Hybrid Journal   (Followers: 5)
BIBECHANA     Open Access   (Followers: 2)
Biomath     Open Access  
BIT Numerical Mathematics     Hybrid Journal   (Followers: 1)
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: 2)
British Journal of Mathematical and Statistical Psychology     Full-text available via subscription   (Followers: 18)
Bruno Pini Mathematical Analysis Seminar     Open Access  
Buletinul Academiei de Stiinte a Republicii Moldova. Matematica     Open Access   (Followers: 13)
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: 3)
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: 2)
Bulletin of the Brazilian Mathematical Society, New Series     Hybrid Journal  
Bulletin of the Iranian Mathematical Society     Hybrid Journal  
Bulletin of the London Mathematical Society     Hybrid Journal   (Followers: 3)
Bulletin of the Malaysian Mathematical Sciences Society     Hybrid Journal  
Cadernos do IME : Série Matemática     Open Access   (Followers: 1)
Calculus of Variations and Partial Differential Equations     Hybrid Journal  
Canadian Journal of Mathematics / Journal canadien de mathématiques     Hybrid Journal  
Canadian Journal of Science, Mathematics and Technology Education     Hybrid Journal   (Followers: 22)
Canadian Mathematical Bulletin     Hybrid Journal  
Carpathian Mathematical Publications     Open Access   (Followers: 1)
Catalysis in Industry     Hybrid Journal   (Followers: 1)
CEAS Space Journal     Hybrid Journal   (Followers: 3)
CHANCE     Hybrid Journal   (Followers: 5)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chaos, Solitons & Fractals : X     Open Access  
ChemSusChem     Hybrid Journal   (Followers: 8)
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  
Ciencia     Open Access   (Followers: 1)
Clean Air Journal     Full-text available via subscription   (Followers: 1)
CODEE Journal     Open Access   (Followers: 3)
Cogent Mathematics     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 3)
Collectanea Mathematica     Hybrid Journal  
College Mathematics Journal     Hybrid Journal   (Followers: 4)
COMBINATORICA     Hybrid Journal  
Combinatorics, Probability and Computing     Hybrid Journal   (Followers: 4)
Combustion Theory and Modelling     Hybrid Journal   (Followers: 15)
Commentarii Mathematici Helvetici     Hybrid Journal  
Communications in Advanced Mathematical Sciences     Open Access  
Communications in Combinatorics and Optimization     Open Access  
Communications in Contemporary Mathematics     Hybrid Journal  
Communications in Mathematical Physics     Hybrid Journal   (Followers: 4)
Communications On Pure & Applied Mathematics     Hybrid Journal   (Followers: 4)
Complex Analysis and its Synergies     Open Access   (Followers: 3)
Complex Variables and Elliptic Equations: An International Journal     Hybrid Journal  
Composite Materials Series     Full-text available via subscription   (Followers: 9)
Compositio Mathematica     Full-text available via subscription  
Comptes Rendus Mathematique     Full-text available via subscription  
Computational and Applied Mathematics     Hybrid Journal   (Followers: 4)
Computational and Mathematical Methods     Hybrid Journal  
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: 9)
Computational Mechanics     Hybrid Journal   (Followers: 5)
Computational Methods and Function Theory     Hybrid Journal  
Computational Optimization and Applications     Hybrid Journal   (Followers: 9)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 11)
Concrete Operators     Open Access   (Followers: 4)
Confluentes Mathematici     Hybrid Journal  
Contributions to Discrete Mathematics     Open Access   (Followers: 3)
Contributions to Game Theory and Management     Open Access  
COSMOS     Hybrid Journal  
Cryptography and Communications     Hybrid Journal   (Followers: 13)
Cuadernos de Investigación y Formación en Educación Matemática     Open Access  
Cubo. A Mathematical Journal     Open Access  
Current Research in Biostatistics     Open Access   (Followers: 8)
Czechoslovak Mathematical Journal     Hybrid Journal   (Followers: 1)
Daya Matematis : Jurnal Inovasi Pendidikan Matematika     Open Access   (Followers: 2)
Demographic Research     Open Access   (Followers: 15)
Demonstratio Mathematica     Open Access  

        1 2 3 4 5 | Last

Similar Journals
Journal Cover
Acta Mathematica Hungarica
Journal Prestige (SJR): 0.452
Citation Impact (citeScore): 1
Number of Followers: 2  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1588-2632 - ISSN (Online) 0236-5294
Published by Springer-Verlag Homepage  [2626 journals]
  • Notes on extended equation solvability and identity checking for groups
    • Abstract: Every finite non-nilpotent group can be extended by a term operation such that solving equations in the resulting algebra is NP-complete and checking identities is co-NP-complete. This result was firstly proven by Horváth and Szabó; the term constructed in their proof depends on the underlying group. In this paper we provide a uniform term extension that induces hard problems. In doing so we also characterize a big class of solvable, non-nilpotent groups for which extending by the commutator operation suffices.
      PubDate: 2019-03-13
  • Homotopy investigation of classifying spaces of cobordisms of singular
    • Abstract: The classifying spaces of cobordisms of singular maps have two fairly different constructions. We expose a homotopy theoretical connection between them. As a corollary we show that the classifying spaces in some cases have a simple product structure.
      PubDate: 2019-02-28
  • The Fitting length of a product of mutually permutable finite groups
    • Abstract: Let the finite soluble group \({G = G_{1}G_{2} \cdots G_{r}}\) be the product of pairwise mutually permutable subgroups \({G_{1}, G_{2}, \ldots, G_{r}}\) , let h(G) and \({\ell_{p}(G)}\) be respectively the Fitting length and the p-length of G. The aim of this paper is to prove that \({h(G) \leq {\rm max} \{h(G_{i}) \mid i = 1, 2, \ldots, r\}+1}\) and \({\ell_{p}(G) \leq {\rm max} \{\ell_{p}(G_{i}) \mid i = 1, 2, \ldots, r\}+1}\) .
      PubDate: 2019-02-26
  • On the magnitude of the roots of some well-known enumerative polynomials
    • Abstract: We present estimations of the roots of r-Dowling, r-Lah and r-Dowling–Lah polynomials. It is known that these polynomials have simple, real and non-positive roots. We give bounds for them and we also compute the real magnitude of the roots via computational methods.
      PubDate: 2019-02-26
  • Commutativity in the lattice of topologizing filters of a ring –
           localization and congruences
    • Abstract: The order dual \({[{\rm Fil}{R_{R}}]^{{\rm du}}}\) of the set \({{\rm Fil}{R_{R}}}\) of all right topologizing filters on a fixed but arbitrary ring R is a complete lattice ordered monoid with respect to the (order dual) of inclusion and a monoid operation ‘ \({:}\) ’ that is, in general, noncommutative. It is known that \({[{\rm Fil}{R_{R}}]^{{\rm du}}}\) is always left residuated, meaning, for each pair \({\mathfrak{F}, \mathfrak{G} \in {\rm Fil}{R_{R}}}\) there exists a smallest \({\mathfrak{H} \in {\rm Fil}{R_{R}}}\) such that \({\mathfrak{H}: \mathfrak{G} \supseteq \mathfrak{F}}\) , but is not, in general, right residuated (there exists a smallest \({\mathfrak {H}}\) such that \({\mathfrak{G} : \mathfrak{H} \supseteq \mathfrak{F}}\) ). Rings R for which \({[{\rm Fil}{R_{R}}]^{{\rm du}}}\) is both left and right residuated are shown to satisfy the DCC on left annihilator ideals and possess only finitely many minimal prime ideals. It is shown that every maximal ideal P of a commutative ring R gives rise to an onto homomorphism of lattice ordered monoids \({\hat{\varphi}_{P}}\) from \({[{\rm Fil}{R}]^{{\rm du}}}\) to \({[{\rm Fil}{R_{P}}]^{{\rm du}}}\) where RP denotes the localization of R at P. The kernel \({\equiv_{\hat{\varphi}_{P}}}\) of \({\hat{\varphi}_{P}}\) is a congruence on \({[{\rm Fil}{R}]^{{\rm du}}}\) whose properties we explore. Defining \({{\rm Rad}({\rm Fil}{R})}\) to be the intersection of all congruences \({\equiv_{\hat{\varphi}_{P}}}\) as P ranges through all maximal ideals of R, we show that for commutative VNR rings R, \({{\rm Rad}({\rm Fil}{R})}\) is trivial (the identity congruence) precisely if R is noetherian (and thus a finite product of fields). It is shown further that for arbitrary commutative rings R, \({{\rm Rad}({\rm Fil}{R})}\) is trivial whenever \({{\rm Fil}{R}}\) is commutative (meaning, the monoid operation ‘ \({:}\) ’ on \({{\rm Fil}{R}}\) is commutative). This yields, for such rings R, a subdirect embedding of \({[{\rm ...
      PubDate: 2019-02-26
  • Recurrence relation and multi-indexed polynomials of the second kind
    • Abstract: Exceptional orthogonal polynomials fulfil recurrence relations with constant, and with variable dependent coefficients. Considering the second type relations we can define multi-indexed polynomials of the second kind. In some cases they are also exceptional orthogonal polynomials. The other types of multi-indexed polynomials of the second kind are investigated in case of 2-step Darboux transform.
      PubDate: 2019-02-26
  • On an inverse problem in additive number theory
    • Abstract: Let A be a sequence of positive integers and P(A) be the set of all integers which can be represented as the finite sum of distinct terms of A. By improving a result of Hegyvári, Chen and Fang [2] proved that, for a sequence of integers \({B = \{b_{1} < b_{2} < \cdots \}}\) , if \({b_{1} \in \{4, 7, 8\} \cup \{b : b \geq 11\}}\) and \({b_{n+1} \geq 3b_{n} + 5}\) for all \({n \geq 1}\) , then there exists an infinite sequence A of positive integers for which \({P(A) = \mathbb{N} \setminus B}\) ; on the other hand, if b2 =  3b1 +  4, then such A does not exist. In this paper, for b2 = 3b1 +  5, we determine the critical value for b3 such that there exists an infinite sequence A of positive integers for which \({P(A) = \mathbb{N} \setminus B}\) .
      PubDate: 2019-02-22
  • On the reverse Orlicz–Lorentz Busemann–Petty centroid
    • Abstract: This paper studies the extrema of some affine invariant functionals related to the volume of the Orlicz–Lorentz centroid body introduced by Nguyen. We obtain some variants of the Orlicz–Lorentz Busemann–Petty centroid inequality, and also prove the reverse form of these inequalities in the two-dimensional case.
      PubDate: 2019-02-22
  • On the solutions of a Lebesgue–Nagell type equation
    • Abstract: We find all positive integer solutions in x, y and n of \({x^{2}+19^{2k+1}=4y^{n}}\) for any non-negative integer k.
      PubDate: 2019-02-15
  • A p -nilpotency criterion for finite groups
    • Abstract: We prove a p-nilpotency criterion for finite groups in terms of the element orders of its p′-reduced sections that extends a nilpotency criterion by Tărnăuceanu.
      PubDate: 2019-02-01
  • On the Diophantine equation $${y^{p} = \frac{f(x)}{g(x)}}$$ y p = f ( x )
           g ( x )
    • Abstract: We consider the Diophantine equation $$y^{p} = \frac{f(x)}{g(x)},$$ where \({x \in \mathbb{Z}}\) and \({y \in \mathbb{Q}}\) are unknowns, f(x) and g(x) are non-zero integer polynomials in variable x and p is prime. We give bounds for x, when \({(x, y) \in \mathbb{Z} \times \mathbb{Q}}\) is a solution of the equation. This improves the results of some recent papers.
      PubDate: 2019-02-01
  • On the behavior of roots of trinomial equations
    • Abstract: The main purpose of this paper is to investigate the distribution, simplicity and monotonicity of the roots of a class of trinomial equations that appears in certain financial mathematics problems. Furthermore, we show that it is possible to decompose some classes of trinomial equations into polynomials generated by a three term recurrence relation.
      PubDate: 2019-02-01
  • Spectral synthesis for the space of tempered solutions of a convolution
           system on discrete Abelian groups
    • Abstract: We consider a problem of spectral synthesis in the topological vector space \({\mathcal{M}(G)}\) of tempered functions on a discrete Abelian group G. It is proved that the space of tempered solutions of a convolution system on discrete Abelian groups admits spectral synthesis, that is the space of tempered solutions of a convolution system coincides with the closed linear span in \({\mathcal{M}(G)}\) of all exponential monomial solutions of this system.
      PubDate: 2019-02-01
  • Spherical and moment functions on the affine group of SU ( n )
    • Abstract: Moments of probability measures on a group can be obtained from so called (generalized) moment functions of a given order. Characterization theorems for moment function sequences on different types of groups and hypergroups have been obtained. We study spherical and moment functions on affine groups and describe spherical and moment functions on the affine group of the SU(n) group.
      PubDate: 2019-02-01
  • Weak compactness and metrizability of Mackey*-bounded sets in Fréchet
    • Abstract: Motivated by the density condition in the sense of Heinrich for Fréchet spaces and by some results of Schlüchtermann and Wheeler for Banach spaces, we characterize in terms of certain weakly compact resolutions those Fréchet spaces enjoying the property that each bounded subset of its Mackey* dual is metrizable. We also characterize those Köthe echelon Fréchet spaces \({\lambda _{p}(A)}\) as well as those Fréchet spaces Ck (X) of real-valued continuous functions equipped with the compact-open topology that enjoy this property.
      PubDate: 2019-02-01
  • Min-max property in metric spaces with convex structure
    • Abstract: In the setting of convex metric spaces, we introduce the two geometric notions of uniform convexity in every direction as well as sequential convexity. They are used to study a concept of proximal normal structure. We also consider the class of noncyclic relatively nonexpansive mappings and analyze the min-max property for such mappings. As an application of our main results we conclude with some best proximity pair theorems for noncyclic mappings.
      PubDate: 2019-02-01
  • An isomorphic property in spaces of compact operators and some classes of
           operators on C ( K , X )
    • Abstract: Let \({K_{w^{*}}(X^{*},Y)}\) denote the set of all w*−w continuous compact operators from X* to Y. We investigate whether the space \({K_{w^{*}}(X^{*},Y)}\) has property RDP p * ( \({1\le p < \infty}\) ) when X and \({Y}\) have the same property. Suppose X and Y are Banach spaces, K is a compact Hausdorff space, \({\Sigma}\) is the \({\sigma}\) -algebra of Borel subsets of K, C(K,X) is the Banach space of all continuous X-valued functions (with the supremum norm), and \({T: C(K,X)\to Y}\) is a strongly bounded operator with representing measure \({m: \Sigma \to L(X,Y)}\) . We show that if T is a strongly bounded operator and \({\hat{T}: B(K, X) \to Y}\) is its extension, then T* is p-convergent if and only if \({\hat{T}^{*}}\) is p-convergent, for \({1\le p < \infty}\) .
      PubDate: 2019-02-01
  • Characterization of reflexive closure of some operator algebras acting on
           Hilbert $${C^{\star}}$$ C ⋆ -modules
    • Abstract: Let \({\mathcal M}\) be a Hilbert \({C^{*}}\) -module over a \({C^{*}}\) -algebra \({\mathcal A}\) . Suppose that \({\mathcal{K}(\mathcal{M})}\) is the space of compact operators on \({\mathcal M}\) and the bounded anti-homomorphism \({\rho \colon \mathcal{A}\rightarrow \mathcal{B}(\mathcal{M})}\) defined by \({\rho(a)(m)=ma}\) for all \({a\in\mathcal{A}}\) and \({m\in\mathcal{M}}\) . In this paper, we first provide some characterizations of module maps on Banach modules over Banach algebras by several local conditions (some of our results are a generalization of previous results) and then apply them to characterize the reflexive closure of \({\mathcal{K}(\mathcal{M})}\) and \({\rho(\mathcal{A})}\) , i.e., \({{\rm Alg}{\rm Lat} \mathcal{K}(\mathcal{M})}\) and \({{\rm Alg}{\rm Lat} \rho(\mathcal{A})}\) , where we think of \({\mathcal{K}(\mathcal{M})}\) and \({\rho(\mathcal{A})}\) as operator algebras acting on \({\mathcal M}\) . As an application of our results on reflexive closure of \({\mathcal{K}(\mathcal{M})}\) and \({\rho(\mathcal{A})}\) , a characterization of commutativity for \({C^{*}}\) -algebras is given.
      PubDate: 2019-02-01
  • On the convergence of permutations of multiple orthogonal series
    • Abstract: We provide a characterization of coefficients of a general orthogonal double-index series which allows existence of an a.e. convergent rearrangement. Namely, we show that for any sequence of numbers \({(a_{\mathbf{n}})_{\mathbf{n}\in\mathbb{N}^d}}\) the condition \({\sum_{\mathbf{n}\in\mathbb{N}^d} a_{\mathbf{n}}^{2}{\rm log}^{2} a_{\mathbf{n}}^{2} < \infty}\) is equivalent to the existence of an injective map \({\varrho\colon\mathbb{N}^{d} \rightarrow \mathbb{N}^{d}}\) such that the multiple series \({\sum_{\mathbf{n}\in\mathbb{N}^d} a_{\varrho(\mathbf{n})}\Phi_{\varrho(\mathbf{n})}}\) converges a.e. for any orthonormal system of functions \({(\Phi_{\mathbf{n}})_{\mathbf{n}\in\mathbb{N}^d}}\) . To this end, a Menshov-type lemma for arbitrary subsets of \({\mathbb{N}^d}\) is proved.
      PubDate: 2019-02-01
  • Generalizations of some results about the regularity properties of an
           additive representation function
    • Abstract: Let \({A = \{a_{1},a_{2},\dots{} \}}\) \({(a_{1} < a_{2} < \cdots )}\) be an infinite sequence of nonnegative integers, and let \({R_{A,2}(n)}\) denote the number of solutions of \({a_{x}+a_{y}=n}\) \({(a_{x},a_{y} \in A)}\) . P. Erdős, A. Sárközy and V. T. Sós proved that if \({\lim_{N\to\infty}\frac{B(A,N)}{\sqrt{N}}=+\infty}\) then \({ \Delta_{1}(R_{A,2}(n)) }\) cannot be bounded, where \({B(A,N)}\) denotes the number of blocks formed by consecutive integers in A up to N and \({\Delta_{l}}\) denotes the l-th difference. Their result was extended to \({\Delta_{l}(R_{A,2}(n))}\) for any fixed \({l\ge2}\) . In this paper we give further generalizations of this problem.
      PubDate: 2019-02-01
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