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  • A survey on the spectra of the difference operators over the Banach space c
    RACSAM (IF 1.406) Pub Date : 2021-01-15
    P. Baliarsingh, M. Mursaleen, Vladimir Rakočević

    Recently, due to its numerous applications, the spectra of the bounded operators over Banach spaces have been studied extensively. This work aims to collect some of the investigations on the spectra of difference operators or matrices on the Banach space c in the literature and provide a foundation for related problems. To the best of our investigations, the problem has been solved over the sequence

    更新日期:2021-01-15
  • Approximation formulas and inequalities for the Euler-Mascheroni constant
    RACSAM (IF 1.406) Pub Date : 2021-01-13
    Chao-Ping Chen

    Let \(a\in (0, \infty )\) and \(s \in (0, 1)\), and let \(\gamma \) denote the Euler-Mascheroni constant. The sequence \(\{y_n(a, s)\}_{n\in \mathbb {N}}\) is defined by $$\begin{aligned} y_n(a, s)&=\frac{1}{a^s}+\frac{1}{(a+1)^s}+\cdots +\frac{1}{(a+n-1)^s}-\frac{(a+n-1)^{1-s}-a^{1-s}}{1-s} \end{aligned}$$ for each \(n\in \mathbb {N}:=\{1,2,3,\ldots \}\). The sequence \(\{y_n(a, s)\}_{n\in \mathbb

    更新日期:2021-01-14
  • Correction to: Distinguished $$ C_{p}(X) $$ C p ( X ) spaces
    RACSAM (IF 1.406) Pub Date : 2021-01-13
    J. C. Ferrando, J. Ka̧kol, A. Leiderman, S. A. Saxon

    Unfortunately, the reference 19 is updated incorrectly in the original article and the reference 19 should be.

    更新日期:2021-01-13
  • Simplicial fibrations
    RACSAM (IF 1.406) Pub Date : 2021-01-12
    Desamparados Fernández-Ternero, José Manuel García-Calcines, Enrique Macías-Virgós, José Antonio Vilches

    We undertake a systematic study of fibrations in the setting of abstract simplicial complexes, where the concept of “homotopy” has been replaced by that of “contiguity”. Then, a fibration will be a simplicial map satisfying the “contiguity lifting property”. This definition turns out to be equivalent to that introduced by Minian, established in terms of a cylinder construction \(K \times I_m\). This

    更新日期:2021-01-12
  • Global and linear convergence of alternated inertial methods for split feasibility problems
    RACSAM (IF 1.406) Pub Date : 2021-01-10
    Yekini Shehu, Qiao-Li Dong, Lu-Lu Liu

    The focus of this paper is to introduce algorithms with alternated inertial step to solve split feasibility problems. We obtain global convergence of the sequences of iterates generated by the proposed methods under some appropriate conditions. When the split feasibility problem satisfies some bounded linear regularity property, we show that the generated sequences converge linearly. As far as we know

    更新日期:2021-01-10
  • Frequent hypercyclicity of weighted composition operators on the space of smooth functions
    RACSAM (IF 1.406) Pub Date : 2021-01-09
    Krzysztof Piszczek, Adam Przestacki

    We prove that every hypercyclic weighted composition operator acting on the space of smooth functions on the real line is already frequently hypercyclic. Moreover, for a given frequently hypercyclic weighted composition operator \(C_{w,\psi }\) we show that \(C^\infty ({\mathbb {R}})=FHC(C_{w,\psi })+FHC(C_{w,\psi })\) and that \(FHC(C_{w,\psi })\cup \{0\}\) contains a closed infinite dimensional subspace

    更新日期:2021-01-10
  • Modulus support functionals, Rajchman measures and peak functions
    RACSAM (IF 1.406) Pub Date : 2021-01-09
    L. Golinskii, V. Kadets

    In 2000 Victor Lomonosov suggested a counterexample to the complex version of the Bishop–Phelps theorem on modulus support functionals. We discuss the \(c_0\)-analog of that example and demonstrate that the set of sup-attaining functionals is non-trivial, thus answering an open question, asked in Kadets et al. (The mathematical legacy of Victor Lomonosov. Operator theory. Advances in analysis and geometry

    更新日期:2021-01-10
  • Lebesgue–Stieltjes combined $$\Diamond _\alpha $$ ◊ α -measure and integral on time scales
    RACSAM (IF 1.406) Pub Date : 2021-01-08
    Guangzhou Qin, Chao Wang

    In this paper, we introduce the concepts of Lebesgue–Stieltjes \(\Diamond _\alpha \)-measure, \(\Diamond _\alpha \)-measurable function and \(\Diamond _\alpha \)-integral. Based on the theory of combined measurability on time scales, some basic properties including the relationships, the extensions and the composition theorems are established. Particularly, through the switch coefficient of combined

    更新日期:2021-01-10
  • Third Hankel determinant for univalent starlike functions
    RACSAM (IF 1.406) Pub Date : 2021-01-08
    Paweł Zaprawa, Milutin Obradović, Nikola Tuneski

    In this paper we obtain the bound of the third Hankel determinant $$\begin{aligned} H_3(1) = \left| \begin{array}{c@{\quad }c@{\quad }c} 1 &{} a_2&{} a_3\\ a_2 &{} a_3&{} a_4\\ a_3 &{} a_4&{} a_5\\ \end{array} \right| \end{aligned}$$ for the class \({\mathcal {S}}^*\) of univalent starlike functions, i.e. the functions which satisfy in the unit disk the condition \({{\,\mathrm{Re}\,}}\frac{zf'(z)}{f(z)}>0\)

    更新日期:2021-01-08
  • Monotonicity and convexity involving generalized elliptic integral of the first kind
    RACSAM (IF 1.406) Pub Date : 2021-01-07
    Tie-Hong Zhao, Miao-Kun Wang, Yu-Ming Chu

    In this paper, we present the monotonicity properties of the ratio between generalized elliptic integral of the first kind \({\mathcal {K}}_a(r)\) and its approximation \(\log [1+2/(ar')]\), and also the convexity (concavity) of their difference for \(a\in (0,1/2]\). As an application, we give new bounds for generalized Grötzsch ring function \(\mu _a(r)\) and a upper bound for \({\mathcal {K}}_a(r)\)

    更新日期:2021-01-07
  • Polynomial–Sinc collocation method combined with the Legendre–Gauss quadrature rule for numerical solution of distributed order fractional differential equations
    RACSAM (IF 1.406) Pub Date : 2021-01-07
    Nasrin Moshtaghi, Abbas Saadatmandi

    In the current work, we present an efficient collocation method based on the polynomial–Sinc combined with the Legendre–Gauss quadrature rule for numerically solving a class of distributed order fractional differential equations. This method uses Lagrange approximation at Sinc points. The main purpose of this work is to generalize polynomial–Sinc method to the fractional calculus. The convergence of

    更新日期:2021-01-07
  • A new approach towards estimating the n -dimensional Bohr radius
    RACSAM (IF 1.406) Pub Date : 2021-01-07
    Luis Bernal-González, Hernán J. Cabana, Domingo García, Manuel Maestre, Gustavo A. Muñoz-Fernández, Juan B. Seoane-Sepúlveda

    A new estimate for the Bohr radius of the family of holomorphic functions in the n-dimensional polydisk is provided. This estimate, obtained via a new approach, is sharper than those that are known up to date.

    更新日期:2021-01-07
  • Proof of a generalization of the (C.2) supercongruence of Van Hamme
    RACSAM (IF 1.406) Pub Date : 2021-01-07
    Victor J. W. Guo

    We prove some q-supercongruences for certain truncated basic hypergeometric series by making use of Andrews’ multiseries generalization of the Watson transformation, the creative microscoping method, and the Chinese remainder theorem for coprime polynomials. More precisely, we confirm Conjectures 5.2 and 5.3 in Guo (Adv Appl Math 116:Art. 102016, 2020). As a conclusion, we also prove Conjecture 4.3

    更新日期:2021-01-07
  • Existence and uniqueness of positive solutions for a class of singular fractional differential equation with infinite-point boundary value conditions
    RACSAM (IF 1.406) Pub Date : 2021-01-07
    J. Caballero, J. Harjani, K. Sadarangani

    In this paper, we present a result about the existence and uniqueness of positive solutions for a class of singular fractional differential equations with infinite-point boundary value conditions. The main tool used in the proof of the results is a fixed point theorem.

    更新日期:2021-01-07
  • New improvements of Jensen’s type inequalities via 4-convex functions with applications
    RACSAM (IF 1.406) Pub Date : 2021-01-06
    Muhammad Adil Khan, Shahid Khan, Ɖilda Pečarić, Josip Pečarić

    In this article, we present some new improvements of Jensen’s type inequalities via 4-convex and Green functions. These improvements are demonstrated in discrete as well as in integral versions. The aforesaid results enable us to give some improvements of Jensen’s and the Jensen–Steffensen inequalities. Also, we present some improvements of the reverse Jensen’s and the Jensen–Steffensen inequalities

    更新日期:2021-01-07
  • On Mazurkiewicz’s sets, thin $$\sigma $$ σ -ideals of compact sets and the space of probability measures on the rationals
    RACSAM (IF 1.406) Pub Date : 2021-01-06
    R. Pol, P. Zakrzewski

    We shall establish some properties of thin \(\sigma \)-ideals of compact sets in compact metric spaces (in particular, the \(\sigma \)-ideals of compact null-sets for thin subadditive capacities), and we shall refine the celebrated theorem of David Preiss that there exist compact non-uniformly tight sets of probability measures on the rationals. Both topics will be based on a construction of Stefan

    更新日期:2021-01-07
  • Lineability of the set of supporting vectors
    RACSAM (IF 1.406) Pub Date : 2021-01-05
    Francisco Javier García-Pacheco

    The set of supporting vectors of a continuous linear operator \(T:X\rightarrow Y\) between normed spaces, denoted by \(\mathrm {suppv}(T)\) since 2017, is defined as \(\mathrm {suppv}(T):=\{x\in X:\Vert T(x)\Vert =\Vert T\Vert \Vert x\Vert \}\). In this manuscript, we study the lineability and coneability properties of \(\mathrm {suppv}(T)\), reaching both positive and negative results depending on

    更新日期:2021-01-06
  • Simple, accurate, asymptotic estimates for the ratio of two Gamma functions
    RACSAM (IF 1.406) Pub Date : 2021-01-05
    Vito Lampret

    Several new, accurate, asymptotic estimates for the ratio of two Gamma functions, \(Q_{\varGamma }(x,a,b):=\frac{\varGamma (x+a)}{\varGamma (x+b)}\), are obtained on the basis of Stirling’s approximation formula for the \(\varGamma \) function.

    更新日期:2021-01-05
  • A ratio of finitely many gamma functions and its properties with applications
    RACSAM (IF 1.406) Pub Date : 2021-01-04
    Feng Qi, Wen-Hui Li, Shu-Bin Yu, Xin-Yu Du, Bai-Ni Guo

    In the paper, the authors establish an inequality involving exponential functions and sums, introduce a ratio of finitely many gamma functions, discuss properties, including monotonicity, logarithmic convexity, (logarithmically) complete monotonicity, and the Bernstein function property, of the newly introduced ratio, and construct two inequalities of multinomial coefficients and multivariate beta

    更新日期:2021-01-04
  • On weakly compact sets in $$C\left( X\right) $$ C X
    RACSAM (IF 1.406) Pub Date : 2021-01-04
    J. C. Ferrando, S. López-Alfonso

    A subset A of a locally convex space E is called (relatively) sequentially complete if every Cauchy sequence \(\left\{ x_{n}\right\} _{n=1}^{\infty }\) in E contained in A converges to a point \(x\in A\) (a point \(x\in E\)). Asanov and Velichko proved that if X is countably compact, every functionally bounded set in \(C_{p}\left( X\right) \) is relatively compact, and Baturov showed that if X is a

    更新日期:2021-01-04
  • New bounds of Wilker- and Huygens-type inequalities for inverse trigonometric functions
    RACSAM (IF 1.406) Pub Date : 2021-01-02
    Xiao-Diao Chen, Hui Wang, Kang Yang, Jin Xie

    By using two-parameter functions, this paper presents a family of new Wilker and Huygens type inequalities involving inverse trigonometric functions. It can recover parts of previous results, and can also achieve much better approximation performance than those of prevailing methods. The application of approximating the integral computation is shown by numerical examples, which shows the better approximation

    更新日期:2021-01-03
  • Analytical Meir–Keeler type contraction mappings and equivalent characterizations
    RACSAM (IF 1.406) Pub Date : 2021-01-02
    Abhijit Pant, Rajendra Prasad Pant, Wutiphol Sintunavarat

    The aim of this paper is to obtain a fixed point theorem which gives a new solution to the Rhoades’ problem on the existence of contractive mappings that admit discontinuity at the fixed point; and it is the first Meir–Keeler type solution of this problem. We prove that our theorem characterizes the completeness of the metric space. We also give the structure of complete subspaces of the real line

    更新日期:2021-01-03
  • Wilker inequalities of exponential type for circular functions
    RACSAM (IF 1.406) Pub Date : 2021-01-02
    Ling Zhu

    This paper established two new Wilker’s inequalities of exponential type for the functions \(\left( \left( \sin x\right) /x\right) ^{2}+\left( \tan x\right) /x-2\) and \(\left( x/\left( \sin x\right) \right) ^{2}+x/\left( \tan x\right) -2\) bounded by the functions $$\begin{aligned} \frac{8}{45}x^{4}\left( \frac{\tan (\sqrt{61}x/7)}{\sqrt{61}x/7}\right) ^{42/61} \end{aligned}$$ and $$\begin{aligned}

    更新日期:2021-01-02
  • On lineability of families of non-measurable functions of two variable
    RACSAM (IF 1.406) Pub Date : 2021-01-02
    Tomasz Natkaniec

    A function \(F:\mathbb {R}^2\rightarrow \mathbb {R}\) is sup-measurable if, for each (Lebesgue) measurable function \(f:\mathbb {R}\rightarrow \mathbb {R}\), the Carathéodory superposition \(F_f:\mathbb {R}\rightarrow \mathbb {R}\) given by \(F_f: x\mapsto F(x,f(x))\) is measurable. The existence of non-measurable sup-measurable functions is independent of ZFC. We prove, assuming CH, that the family

    更新日期:2021-01-02
  • On $$\mu $$ μ -deferred statistical convergence and strongly deferred summable functions
    RACSAM (IF 1.406) Pub Date : 2021-01-02
    Mikail Et, Pinakadhar Baliarsingh, Hacer Şengül Kandemir, Mehmet Küçükaslan

    In this paper we introduce the concepts of strongly deferred Cesàro summable and \(\mu \)-deferred statistical convergence of real-valued functions \(x=x(t)\) which are measurable (in the Lebesgue sense) in the interval \([1,\infty )\). In addition, the relations between the set of strong deferred Cesàro summable and \(\mu \)-deferred statistical convergent of functions have been examined under some

    更新日期:2021-01-02
  • A new approach to fixed point theorems in compact 2-generalized metric spaces
    RACSAM (IF 1.406) Pub Date : 2021-01-02
    Nguyen Van Dung

    In this paper, we present a new approach to solve fixed point theorems in compact 2-generalized metric spaces. The approach is to show that the restriction of a given 2-generalized metric to the closure of a certain orbit is a metric. By using the new approach and constructing a counterexample, we completely answer the open question about the role of the continuity of the 2-generalized metric posed

    更新日期:2021-01-02
  • On quantum hybrid fractional conformable differential and integral operators in a complex domain
    RACSAM (IF 1.406) Pub Date : 2021-01-02
    Rabha W. Ibrahim, Dumitru Baleanu

    Newly, the hybrid fractional differential operator (HFDO) is presented and studied in Baleanu et al. (Mathematics 8.3:360, 2020). This work deals with the extension of HFDO to the complex domain and its generalization by using the quantum calculus. The outcome of the above conclusion is a q-HFDO, which will employ to introduce some classes of normalized analytic functions containing the well-known

    更新日期:2021-01-02
  • Closed formulas and determinantal expressions for higher-order Bernoulli and Euler polynomials in terms of Stirling numbers
    RACSAM (IF 1.406) Pub Date : 2021-01-02
    Muhammet Cihat Dağlı

    In this paper, the author presents several closed forms and determinantal expressions involving Stirling numbers of the second kind for higher-order Bernoulli and Euler polynomials by applying the Faà di Bruno formula and some properties of Bell polynomials.

    更新日期:2021-01-02
  • On the Cusa–Huygens inequality
    RACSAM (IF 1.406) Pub Date : 2021-01-01
    Yogesh J. Bagul, Christophe Chesneau, Marko Kostić

    Sharp bounds of various kinds for the famous unnormalized sinc function defined by \((\sin x)/x\) are useful in mathematics, physics and engineering. In this paper, we reconsider the Cusa–Huygens inequality by solving the following problem: given real numbers \(a,b, c\in {{\mathbb {R}}}\) and \(T\in (0,\pi /2],\) we find the necessary and sufficient conditions such that the inequalities $$\begin{aligned}

    更新日期:2021-01-01
  • Identities and relations for Hermite-based Milne–Thomson polynomials associated with Fibonacci and Chebyshev polynomials
    RACSAM (IF 1.406) Pub Date : 2020-11-27
    Neslihan Kilar, Yilmaz Simsek

    The aim of this paper is to give many new and interesting identities, relations, and combinatorial sums including the Hermite-based Milne-Thomson type polynomials, the Chebyshev polynomials, the Fibonacci-type polynomials, trigonometric type polynomials, the Fibonacci numbers, and the Lucas numbers. By using Wolfram Mathematica version 12.0, we give surfaces graphics and parametric plots for these

    更新日期:2020-11-27
  • Distinguished $$ C_{p}(X) $$ C p ( X ) spaces
    RACSAM (IF 1.406) Pub Date : 2020-11-25
    J. C. Ferrando, J. Ka̧kol, A. Leiderman, S. A. Saxon

    We continue our initial study of \(C_{p}(X) \) spaces that are distinguished, equiv., are large subspaces of \(\mathbb {R}^{X}\), equiv., whose strong duals \(L_{\beta }( X) \) carry the strongest locally convex topology. Many are distinguished, many are not. All \(L_{\beta }(X) \) spaces are, as are all metrizable \(C_{p}(X) \) and \( C_{k} ( X) \) spaces. To prove a space \(C_{p}(X) \) is not distinguished

    更新日期:2020-11-25
  • Divisibility properties of random samples of integers
    RACSAM (IF 1.406) Pub Date : 2020-11-23
    José L. Fernández, Pablo Fernández

    This paper is devoted to survey the rich theory, some of it quite recent, concerning the divisibility properties, of various kinds, of random r-tuples of positive integers.

    更新日期:2020-11-25
  • Topological realizations of groups in Alexandroff spaces
    RACSAM (IF 1.406) Pub Date : 2020-11-23
    Pedro J. Chocano, Manuel A. Morón, Francisco Ruiz del Portal

    We prove that every group can be realized as the homeomorphism group and as the group of (pointed) homotopy classes of (pointed) self-homotopy equivalences of infinitely many non-homotopy-equivalent Alexandroff spaces.

    更新日期:2020-11-23
  • On pq -fold regular covers of the projective line
    RACSAM (IF 1.406) Pub Date : 2020-11-20
    Sebastián Reyes-Carocca

    Let p and q be odd prime numbers. In this paper we study non-abelian pq-fold regular covers of the projective line, determine algebraic models for some special cases and provide a general isogeny decomposition of the corresponding Jacobian varieties. We also give a classification and description of the one-dimensional families of compact Riemann surfaces as before.

    更新日期:2020-11-21
  • Integrals involving the Legendre Chi function
    RACSAM (IF 1.406) Pub Date : 2020-11-20
    A. Sofo

    In this paper we investigate the representation of integrals involving the Legendre Chi function. We will show that in many cases these integrals take an explicit form involving the Riemann zeta function, the Dirichlet Eta function, Dirichlet lambda function and many other special functions. Some examples illustrating the theorems will be detailed.

    更新日期:2020-11-21
  • Characterizations and representations of left and right hybrid ( b , c )-inverses in rings
    RACSAM (IF 1.406) Pub Date : 2020-11-17
    Huihui Zhu, Liyun Wu, Fei Peng, Pedro Patrício

    Let R be an associative ring with unity 1 and let \(a,b,c\in R\). In this paper, several characterizations for left and right hybrid (b, c)-inverses of a are derived. Moreover, their formulae are given by regularities of certain elements. Then, we give characterizations of right (b, c)-inverses and right annihilator (b, c)-inverses of the product of three elements. Finally, relations among the right

    更新日期:2020-11-18
  • Elementary hypergeometric functions, Heun functions, and moments of MKZ operators
    RACSAM (IF 1.406) Pub Date : 2020-11-10
    Ana-Maria Acu, Ioan Rasa

    We consider some hypergeometric functions and prove that they are elementary functions. Consequently, the second order moments of Meyer-König and Zeller type operators are elementary functions. The higher order moments of these operators are expressed in terms of elementary functions and polylogarithms. Other applications are concerned with the expansion of certain Heun functions in series or finite

    更新日期:2020-11-12
  • Algebraic genericity and summability within the non-Archimedean setting
    RACSAM (IF 1.406) Pub Date : 2020-11-10
    J. Khodabandehlou, S. Maghsoudi, J. B. Seoane-Sepúlveda

    In this paper, we establish the analogue of some recent lineability and algebrability results on the sets of sequences and series within the context of p-adic analysis. More specifically, we prove (among several other results) that: (i) in the space of all p-adic sequences, the set of all convergent sequences for which Cesàro’s Theorem fails is lineable, (ii) the set of all non-absolutely convergent

    更新日期:2020-11-12
  • Sobolev spaces of vector-valued functions
    RACSAM (IF 1.406) Pub Date : 2020-11-09
    Iván Caamaño, Jesús Á. Jaramillo, Ángeles Prieto, Alberto Ruiz de Alarcón

    We are concerned here with Sobolev-type spaces of vector-valued functions. For an open subset \(\Omega \subset {\mathbb {R}}^N\) and a Banach space V, we compare the classical Sobolev space \(W^{1,p}(\Omega , V)\) with the so-called Sobolev–Reshetnyak space \(R^{1,p}(\Omega , V)\). We see that, in general, \(W^{1,p}(\Omega , V)\) is a closed subspace of \(R^{1,p}(\Omega , V)\). As a main result, we

    更新日期:2020-11-09
  • Generalizing separability, precompactness and narrowness in topological groups
    RACSAM (IF 1.406) Pub Date : 2020-11-05
    Taras Banakh, Igor Guran, Alex Ravsky

    We discuss various modifications of separability, precompactness and narrowness in topological groups and test those modifications in the permutation groups S(X) and \(S_{<\omega }(X)\).

    更新日期:2020-11-06
  • Vitali–Hahn–Saks property in coverings of sets algebras
    RACSAM (IF 1.406) Pub Date : 2020-11-05
    S. López-Alfonso

    A subset \(\mathscr {B}\) of an algebra \(\mathscr {A}\) of subsets of \(\varOmega \) is a Nikodým set for \(ba(\mathscr {A})\) if each \(\mathscr {B}\)-pointwise bounded subset M of \(ba(\mathscr {A})\) is uniformly bounded on \(\mathscr {A}\) and \(\mathscr {B}\) is a strong Nikodým set for \(ba(\mathscr {A})\) if each increasing covering \((\mathscr {B}_{m})_{m=1}^{\infty }\) of \(\mathscr {B}\)

    更新日期:2020-11-06
  • Bilinear $$\theta $$ θ -type Calderón–Zygmund operator and its commutator on non-homogeneous weighted Morrey spaces
    RACSAM (IF 1.406) Pub Date : 2020-11-03
    Guanghui Lu

    The main purpose of this paper is to establish the boundedness of bilinear \(\theta \)-type Calderón–Zygmund operator \(T_{\theta }\) and its commutator \([b_{1},b_{2},T_{\theta }]\) generated by the function \(b_{i}\in \widetilde{\mathrm {RBMO}}(\mu )\) with \(i=1,2\) and \(T_{\theta }\) on weighted Morrey space \(L^{p,\kappa ,\varrho }(\omega )\) and weighted weak Morrey space \(WL^{p,\kappa ,\varrho

    更新日期:2020-11-03
  • Lyapunov-type inequalities for a nonlinear fractional boundary value problem
    RACSAM (IF 1.406) Pub Date : 2020-11-02
    Aidyn Kassymov, Berikbol T. Torebek

    In this paper, we obtain a Lyapunov-type and a Hartman–Wintner-type inequalities for a nonlinear fractional hybrid equation with left Riemann–Liouville and right Caputo fractional derivatives of order \(1/2<\alpha \le 1,\) subject to Dirichlet boundary conditions. It is also shown that failure of the Lyapunov-type and Hartman–Wintner-type inequalities, corresponding nonlinear boundary value problem

    更新日期:2020-11-02
  • Almost Kenmotsu $$(k,\mu )'$$ ( k , μ ) ′ -manifolds with Yamabe solitons
    RACSAM (IF 1.406) Pub Date : 2020-11-02
    Yaning Wang

    Let \((M^{2n+1},\phi ,\xi ,\eta ,g)\) be a non-Kenmotsu almost Kenmotsu \((k,\mu )'\)-manifold. If the metric g represents a Yamabe soliton, then either \(M^{2n+1}\) is locally isometric to the product space \(\mathbb {H}^{n+1}(-4)\times \mathbb {R}^n\) or \(\eta \) is a strict infinitesimal contact transformation. The later case can not occur if a Yamabe soliton is replaced by a gradient Yamabe soliton

    更新日期:2020-11-02
  • The $$D_{\pi }$$ D π -property on products of $$\pi $$ π -decomposable groups
    RACSAM (IF 1.406) Pub Date : 2020-11-01
    L. S. Kazarin, A. Martínez-Pastor, M. D. Pérez-Ramos

    The aim of this paper is to prove the following result: Let \(\pi \) be a set of odd primes. If the group \(G=AB\) is the product of two \(\pi \)-decomposable subgroups \(A=A_\pi \times A_{\pi '}\) and \(B=B_\pi \times B_{\pi '}\), then G has a unique conjugacy class of Hall \(\pi \)-subgroups, and any \(\pi \)-subgroup is contained in a Hall \(\pi \)-subgroup (i.e. G satisfies property \(D_{\pi }\))

    更新日期:2020-11-02
  • An algorithm for the split feasible problem and image restoration
    RACSAM (IF 1.406) Pub Date : 2020-10-31
    Raweerote Suparatulatorn, Phakdi Charoensawan, Kanyuta Poochinapan, Supreedee Dangskul

    This paper proposes an accelerated algorithm for the split common fixed point problem, based on viscosity approximation methods and inertial effects. The main result will be applied to image restoration problems. This algorithm is constructed in such a way that its step sizes and the norm of a given linear operator are not related. Under some conditions, the strong convergence of the algorithm is obtained

    更新日期:2020-11-02
  • Čebyšev–Grüss inequalities for $$\alpha $$ α -partial derivatives
    RACSAM (IF 1.406) Pub Date : 2020-10-28
    Chang-Jian Zhao

    The main purpose of the present paper is to introduce a new concept by calculating first order variation of multivariate function, and call it \(\alpha \)-multivariate partial derivatives, which is a generalization of the well-known \(\alpha \)-conformable derivatives. For the \(\alpha \)-multivariate partial derivatives, we prove Lagrange’s, Rolle’s and Cauchy’s mean value theorems in n-dimensional

    更新日期:2020-10-30
  • Nontrivial solution for Schrödinger–Poisson equations involving the fractional Laplacian with critical exponent
    RACSAM (IF 1.406) Pub Date : 2020-10-28
    Xiaojing Feng

    This paper deals with a class of nonlocal Schrödinger equations with critical exponent $$\begin{aligned} \left\{ \begin{array}{llll} (-\Delta )^{s} u+V(x)u-K(x)\phi |u|^{2^*_s-3}u=f(x,u),&{}\quad \mathrm{in}\ \mathbb {R}^3,\\ (-\Delta )^s \phi =K(x)|u|^{2^*_s-1},&{}\quad \mathrm{in}\ \mathbb {R}^3. \end{array}\right. \end{aligned}$$ By employing the mountain pass theorem, concentration-compactness

    更新日期:2020-10-30
  • Some new q -congruences on double sums
    RACSAM (IF 1.406) Pub Date : 2020-10-21
    Xiaoxia Wang, Menglin Yu

    Swisher confirmed an interesting congruence: for any odd prime p, $$\begin{aligned} \sum _{k=0}^{(p-1)/2}(-1)^k(6k+1)\frac{(\frac{1}{2})_k^{3}}{k!^{3}8^k} \sum _{j=1}^{k}\Bigg (\frac{1}{(2j-1)^{2}}-\frac{1}{16j^{2}}\Bigg ) \equiv 0 \pmod {p}, \end{aligned}$$ which was conjectured by Long. Recently, its q-analogue was proved by Gu and Guo. Inspired by their work, we obtain a new similar q-congruence

    更新日期:2020-10-30
  • A sharp lower bound for the complete elliptic integrals of the first kind
    RACSAM (IF 1.406) Pub Date : 2020-10-21
    Zhen-Hang Yang, Jing-Feng Tian, Ya-Ru Zhu

    Let \({\mathcal {K}}\left( r\right) \) be the complete elliptic integrals of the first kind and \(\text{ arth }r\) denote the inverse hyperbolic tangent function. We prove that the inequality $$\begin{aligned} \frac{2}{\pi }{\mathcal {K}}\left( r\right) >\left[ 1-\lambda +\lambda \left( \frac{\text{ arth }r}{r}\right) ^{q}\right] ^{1/q} \end{aligned}$$ holds for \(r\in \left( 0,1\right) \) with the

    更新日期:2020-10-30
  • On the coefficients of $$\mathbf {{\mathcal {B}}_1}(\varvec{\alpha })$$ B 1 ( α ) Bazilevič functions
    RACSAM (IF 1.406) Pub Date : 2020-10-19
    Khadija Bano, Mohsan Raza, Derek K. Thomas

    Denote by \({\mathcal {A}}\), the class of functions f, analytic in \({\mathbb {D}} =\{z:|z|<1\}\) and given by \(f(z)=z+\sum _{n=2}^{\infty }a_{n}z^{n}\) for \(z\in {\mathbb {D}}\), and by \({\mathcal {S}}\) the subset of \({\mathcal {A}}\) whose elements are univalent in \({\mathbb {D}}\). The class \({\mathcal {B}}_{1}(\alpha )\subset {\mathcal {S}}\), of Bazilevič functions is defined by \(Re\dfrac{zf^{\prime

    更新日期:2020-10-20
  • Octahedral norms in free Banach lattices
    RACSAM (IF 1.406) Pub Date : 2020-10-14
    Sheldon Dantas, Gonzalo Martínez-Cervantes, José David Rodríguez Abellán, Abraham Rueda Zoca

    In this paper, we study octahedral norms in free Banach lattices FBL[E] generated by a Banach space E. We prove that if E is an \(L_1(\mu )\)-space, a predual of von Neumann algebra, a predual of a JBW\(^*\)-triple, the dual of an M-embedded Banach space, the disc algebra or the projective tensor product under some hypothesis, then the norm of FBL[E] is octahedral. We get the analogous result when

    更新日期:2020-10-14
  • Unified Feng-Liu type fixed point theorems solving control problems
    RACSAM (IF 1.406) Pub Date : 2020-10-13
    Hemant Kumar Nashine, Rabha W. Ibrahim, B. E. Rhoades, Rajendra Pant

    The propose of this work is to study unified Feng-Liu type fixed point theorems using \((\alpha ,\eta )\)-muti-valued admissible mappings with more general contraction condition in complete metric spaces. The obtained results generalize and improve several existing theorems in the literature. We use these results in metric spaces endowed with binary relations and partially ordered sets. Some non-trivial

    更新日期:2020-10-13
  • Approximation properties of mixed sampling-Kantorovich operators
    RACSAM (IF 1.406) Pub Date : 2020-10-11
    Laura Angeloni, Danilo Costarelli, Gianluca Vinti

    In the present paper we study the pointwise and uniform convergence properties of a family of multidimensional sampling Kantorovich type operators. Moreover, besides convergence, quantitative estimates and a Voronovskaja type theorem have been established.

    更新日期:2020-10-11
  • New inequalities for hyperbolic functions based on reparameterization
    RACSAM (IF 1.406) Pub Date : 2020-10-11
    Wangkang Huang, Xiao-Diao Chen, Linqiang Chen, Xiaoyang Mao

    In this paper, we present new inequalities about hyperbolic functions with much better approximation effect. It firstly provides two-sided bounds of \((\sinh (x)/x)^p\) for the case \(p \in (0,1]\), and lower bound for the case \(p \ge \frac{7}{5}\) as well. It also provides inequalities about mixed hyperbolic functions consisting of \(\tanh (x)\) and \(\sinh (x)\). Numerical examples show that the

    更新日期:2020-10-11
  • An accurate and reliable mathematical analytic solution procedure for the EOQ model with non-instantaneous receipt under supplier credits
    RACSAM (IF 1.406) Pub Date : 2020-10-10
    H. M. Srivastava, Kun-Jen Chung, Jui-Jung Liao, Shy-Der Lin, Shih-Fang Lee

    Recently, Huang and Hsu (J Oper Res Soc Jpn 50:1–13, 2007) investigated the retailer’s optimal replenishment policy with non-instantaneous receipt under trade credit and cash discount. Basically, their inventory model is correct and interesting. However, they ignored explorations of interrelations of functional behaviors of the annual total cost to locate the optimal solutions so much so that the accuracy

    更新日期:2020-10-11
  • m -weak group inverses in a ring with involution
    RACSAM (IF 1.406) Pub Date : 2020-10-09
    Yukun Zhou, Jianlong Chen, Mengmeng Zhou

    In a unitary ring with involution, we prove that each element has at most one weak group inverse if and only if each idempotent element has a unique weak group inverse. Furthermore, we define the m-weak group inverse and show some properties of m-weak group inverse.

    更新日期:2020-10-11
  • Global existence combined with general decay of solutions for coupled Kirchhoff system with a distributed delay term
    RACSAM (IF 1.406) Pub Date : 2020-09-26
    Nadjat Doudi, Salah Boulaaras

    The paper deals with the proof of the global existence of solutions for system of nonlinear viscoelastic Kirchhoff system with a distributed delay and general coupling terms in a bounded domain. The current study was performed by using the energy method along with Faedo–Galerkin method and under some suitable conditions in coupling terms parameters. In addition, we prove the stability result by using

    更新日期:2020-09-26
  • Tribonacci numbers that are concatenations of two repdigits
    RACSAM (IF 1.406) Pub Date : 2020-09-15
    Mahadi Ddamulira

    Let \( (T_{n})_{n\ge 0} \) be the sequence of Tribonacci numbers defined by \( T_0=0 \), \( T_1=T_2=1\), and \( T_{n+3}= T_{n+2}+T_{n+1} +T_n\) for all \( n\ge 0 \). In this note, we use of lower bounds for linear forms in logarithms of algebraic numbers and the Baker-Davenport reduction procedure to find all Tribonacci numbers that are concatenations of two repdigits.

    更新日期:2020-09-16
  • Highly tempering infinite matrices II: From divergence to convergence via Toeplitz–Silverman matrices
    RACSAM (IF 1.406) Pub Date : 2020-09-15
    L. Bernal-González, J. Fernández-Sánchez, J. B. Seoane-Sepúlveda, W. Trutschnig

    It was recently proved by Bernal-González et al. (Rev. R. Acad. Cienc. Exactas Fís. Nat. Ser. A Mat. RACSAM 112(2):341–345, 2018) that for any Toeplitz–Silverman matrix A, there exists a dense linear subspace of the space of all sequences, all of whose nonzero elements are divergent yet whose images under A are convergent. In this paper, we improve and generalize this result by showing that, under

    更新日期:2020-09-15
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