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  • Forbidden subgraphs for graphs with (near) perfect matching to be hamiltonian
    Quaest. Math. (IF 0.619) Pub Date : 2020-05-01
    Xiaojing Yang; Liming Xiong

    Let G = (V (G), E(G)) be a graph. A set M ⊆ E(G) is a matching if no two edges in M share a common vertex. A matching of G is perfect if it covers every vertex in G. A matching of a graph G with odd order is called a near perfect matching if it has edges. In this paper, we completely characterize the forbidden subgraph and pairs of forbidden subgraphs that force a 2-connected graph with a (near) perfect

    更新日期:2020-05-01
  • Non-divisibility of the class number of imaginary quadratic fields and some applications
    Quaest. Math. (IF 0.619) Pub Date : 2020-05-01
    Jinrui Wang

    In 1974, P. Hartung proved the existence of infinitely many imaginary quadratic fields with class numbers not divisible by 3. We generalize this result to show the existence of infinitely many imaginary quadratic fields with class numbers not divisible by any integer n > 2. We conclude by providing some interesting applications.

    更新日期:2020-05-01
  • Invariants for geodesic and F-planar mappings of generalized Riemannian spaces
    Quaest. Math. (IF 0.619) Pub Date : 2020-05-01
    N.O. Vesić; Milan Lj. Zlatanović

    Invariants for geodesic and F-planar mappings defined on a generalized Riemannian space are obtained in this paper. These invariants are generalizations of the Thomas projective parameter and the Weyl projective tensor.

    更新日期:2020-05-01
  • On the incomplete Srivastava’s triple hypergeometric matrix functions
    Quaest. Math. (IF 0.619) Pub Date : 2020-05-01
    Ashish Verma

    The paper proposes to introduce incomplete Srivastava’s triple hypergeometric matrix functions through application of the incomplete Pochhammer matrix symbols. We also derive certain properties such as matrix differential equation, integral formula, reduction formula, recursion formula, recurrence relation and differentiation formula of the incomplete Srivastava’s triple hypergeometric matrix functions

    更新日期:2020-05-01
  • Centralizers and isomorphism preservation of minimal factors of nearring modules
    Quaest. Math. (IF 0.619) Pub Date : 2020-05-01
    Gary L. Peterson; Stuart D. Scott

    If N1 is a nearring, V is a faithful tame N1-module and N2 is a nearring containing N1 such that V is a faithful tame N2-module and the N1- and N2-ideals of V coincide, we study when N1-isomorphic minimal factors of V are N2-isomorphic. We also study a stronger form of such preservation called type preservation. Particular attention is paid to the case where N2 is the nearring of 0-preserving and congruence

    更新日期:2020-05-01
  • The schur multiplier of a nilpotent Lie algebra with derived subalgebra of maximum dimension
    Quaest. Math. (IF 0.619) Pub Date : 2020-05-01
    Farangis Johari; Peyman Niroomand; Afsaneh Shamsaki

    We give a new bound for the dimension of the Schur multiplier of an n-dimensional nilpotent Lie algebra of class c with the derived subalgebra of dimension n − 2. This new bound sharpens the earlier upper bounds on the dimension of Schur multiplier of such Lie algebras, especially for Lie algebras of maximal class.

    更新日期:2020-05-01
  • The diameter of strong orientations of strong products of graphs
    Quaest. Math. (IF 0.619) Pub Date : 2020-05-01
    Irena Hrastnik Ladinek; Simon Špacapan

    Let G and H be graphs, and G H the strong product of G and H. We prove that for any connected graphs G and H there is a strongly connected orientation D of G H such that diam (D) ≤ 2r + 15, where r is the radius of G H. This improves the general bound diam(D) ≤ 2r2 +2r for arbitrary graphs, proved by Chvátal and Thomassen.

    更新日期:2020-05-01
  • Extending partial orders on rings
    Quaest. Math. (IF 0.619) Pub Date : 2020-05-01
    Moreta Findler; Jingjing Ma

    For a commutative ring with identity, it is consistently L∗ if and only if it is consistently O∗. This result is generalized to noncommutative rings with identity in the section 2. In the section 3, it is shown that for any abelian group G and integral domain D, the group ring D[G] is L∗ if and only if it is O∗.

    更新日期:2020-05-01
  • The Banaschewski compactification of an approach space is of Wallman-Shanin-type
    Quaest. Math. (IF 0.619) Pub Date : 2020-05-01
    E. Colebunders; M. Sioen

    For a topological zero-dimensional Hausdorff space (X, ) it is well known that the Banaschewski compactification ζ(X, ) is of Wallman-Shanin-type, meaning that there exists a closed basis (the collection of all clopen sets), such that the Wallman-Shanin compactification with respect to this closed basis is isomorphic to ζ(X, ). For an approach space (X, ) the Wallman-Shanin compactification W (X, )

    更新日期:2020-05-01
  • Mal’tsev and Lawvere functors
    Quaest. Math. (IF 0.619) Pub Date : 2020-05-01
    Dominique Bourn

    We investigate, at the level of functors, the effect of definitions mimicking those of Mal’tsev and naturally Mal’tsev categories, and show that they give rise to the same kind of characterizations. We give, among others, an application concerning the characterization of the Smith=Huq condition.

    更新日期:2020-05-01
  • Generalized Lie triple higher derivable maps on rings
    Quaest. Math. (IF 0.619) Pub Date : 2020-05-01
    Mohd Shuaib Akhtar; Mohammad Ashraf

    Let be a ring containing a nontrivial idempotent with the center Z() and ℕ be the set of all non-negative integers. Let Δ = {Gn}n∈ℕ be a family of mappings Gn : (not necessarily additive) such that , the identity mapping of . Then Δ is said to be a generalized Lie triple higher derivable mapping of holds for all a; b; c ∈ and for each n ∈ ℕ, where is a family of mappings (not necessarily additive)

    更新日期:2020-05-01
  • Rings and subrings of continuous functions with countable range
    Quaest. Math. (IF 0.619) Pub Date : 2020-05-01
    Sudip Kumar Acharyya; Rakesh Bharati; A. Deb Ray

    Intermediate rings of the functionally countable subalgebra of C(X) (i.e., the rings Ac(X) lying between Cc∗(X) and Cc(X)), where X is a Hausdorff zero-dimensional space, are studied in this article. It is shown that the structure space of each Ac(X) is homeomorphic to β0X, the Banaschewski compactification of X. From this a main result of [A. Veisi, ec-filters and ec-ideals in the function-ally countable

    更新日期:2020-05-01
  • Some inequalities for the (p, q)-mixed affine surface areas
    Quaest. Math. (IF 0.619) Pub Date : 2020-02-27
    Weidong Wang; Xia Zhao

    The notion of (p, q)-mixed volume was first introduced by Lutwak, Yang and Zhang in 2018. According to this concept, Li, Wang and Zhou defined the (p, q)- mixed affine surface areas in 2019. In this paper, we establish some inequalities including cyclic inequality, monotonous inequality and product inequality for the (p, q)-mixed affine surface areas.

    更新日期:2020-02-27
  • A note on Aupetit's perturbation theorem
    Quaest. Math. (IF 0.619) Pub Date : 2020-02-27
    Sonja Mouton

    We investigate the different forms of Aupetit's perturbation theorem and its variants, and provide some generalisations.

    更新日期:2020-02-27
  • On the continuous dependence of solutions to a bipolynomial fractional Dirichlet-Laplace problem
    Quaest. Math. (IF 0.619) Pub Date : 2020-02-27
    Marek Majewski

    In the paper, we consider a bipolynomial fractional Dirichlet-Laplace problem with a functional parameter u. The main goal is to prove theorems on the existence and continuous dependence of solution on functional parameter u for the above problem. Since the solution to the above fractional problem is not unique in general, we use some set-valued approach. We consider two cases (depending on a real

    更新日期:2020-02-27
  • Calderón-Zygmund operators on Lipschitz spaces over RD spaces
    Quaest. Math. (IF 0.619) Pub Date : 2020-02-27
    Hongliang Li; Taotao Zheng

    Suppose that (X, d, µ) is a metric measure space of homogeneous type in the sense of Coifman and Weiss with a reverse doubling condition. By establishing the Littlewood-Paley characterization of Lipschitz spaces, a density argument in the weak sense and almost orthogonality estimate we prove that a Caldeŕon-Zygmund operator T is bounded on Lipschitz space if and only if T 1 = 0.

    更新日期:2020-02-27
  • Riemann soliton within the framework of contact geometry
    Quaest. Math. (IF 0.619) Pub Date : 2020-02-27
    M.N. Devaraja; H. Aruna Kumara; V. Venkatesha

    In this paper, we study contact metric manifold whose metric is a Riemann soliton. First, we consider Riemann soliton (g, V ) with V as contact vector field on a Sasakian manifold (M, g) and in this case we prove that M is either of constant curvature +1 (and V is Killing) or D-homothetically fixed η-Einstein manifold (and V leaves the structure tensor ϕ invariant). Next, we prove that if a compact

    更新日期:2020-02-27
  • A group theory approach towards some higher order difference equations, solutions, periodicity and asymptotic behavior
    Quaest. Math. (IF 0.619) Pub Date : 2020-02-27
    Mensah Folly-Gbetoula; Darlison Nyirenda

    In this paper, we apply a group theory method to derive the generators of the Lie algebra for a class of (k+1)th order difference equations. We then find solutions to the difference equations and study periodicity by giving sufficient conditions for existence of certain periodicities. We further look at the asymptotic behaviour of solutions satisfying certain properties. Our results generalise some

    更新日期:2020-02-27
  • On stability and nonstability of systems of functional equations
    Quaest. Math. (IF 0.619) Pub Date : 2020-02-27
    Madjid Eshaghi; Bahman Hayati; Mahdie Kamyar; Hamid Khodaei

    In this paper, we consider the stability and nonstability results for the following system of functional equations where a, b ∈ ℤ\{0}, on r-divisible abelian groups.

    更新日期:2020-02-27
  • Strongly primary ideals in rings with zero-divisors
    Quaest. Math. (IF 0.619) Pub Date : 2020-02-27
    Abdelhaq El Khalfi; Najib Mahdou; Youssef Zahir

    Let A be an integral domain with quotient field K. A. Badawi and E. Houston called a strongly primary ideal I of A if whenever x, y ∈ K and xy ∈ I, we have x ∈ I or y ∈ I for some n ≥ 1. In this note, we study the generalization of strongly primary ideal to the context of arbitrary commutative rings. We define a primary ideal P of A to be strongly primary if for each a, b ∈ A, we have aP ⊆ bA or bnA

    更新日期:2020-02-27
  • Remarks on normal distributive nearlattices
    Quaest. Math. (IF 0.619) Pub Date : 2020-02-27
    Ismael Calomino; Luciano J. González

    In this paper, we present the notions of α-ideal and α-congruence on a distributive nearlattice. We prove that the α-ideals and α-congruences of a normal distributive lattice A are in a one-to-one correspondence with the ideals and congruences of the distributive nearlattice R(A) of the annihilators of A, respectively.

    更新日期:2020-02-27
  • Some information measures in concomitants of generalized order statistics under iterated Farlie-Gumbel-Morgenstern bivariate type
    Quaest. Math. (IF 0.619) Pub Date : 2020-02-27
    H.M. Barakat; I.A. Husseiny

    In this paper, we study the concomitants of generalized order statistics from iterated Farlie-Gumbel-Morgenstern (FGM) bivariate distribution. Three information measures, the Shannon entropy, the Kullback-Leibler distance and the Fisher information number, are derived and studied for this model. For each of these information measures, a computational study is conducted, in which we compare the model

    更新日期:2020-02-27
  • Unit groups of group algebras of groups of order 20
    Quaest. Math. (IF 0.619) Pub Date : 2020-02-27
    Sheere Farhat Ansari; Meena Sahai

    Let F be a finite field of characteristic p. There are five non-isomorphic groups of order 20. The structure of U (FD20) is given in [2, 6, 10] and that of U (FQ20) is given in [3, 6], for p = 2, 5. In this article, the unit groups of the group algebras FG are established for all the remaining groups of order 20, namely, U (FC20), U (F (C10 × C2)), U (FQ20) (the semisimple case) and U (FGA(1, 5)) where

    更新日期:2020-02-27
  • Coefficient estimates for some new classes of bi-Bazilevič functions of Ma-Minda type involving the Sălăgean integro-differential operator
    Quaest. Math. (IF 0.619) Pub Date : 2020-02-27
    Páll-Szabó Ágnes Orsolya; Abbas Kareem Wanas

    In this paper we introduce and investigate new classes of bi-Bazilevič functions of Ma-Minda type involving the Sălăgean integro-differential operator. Bounds of the first three coefficients |a2|, |a3| and |a4| are given.

    更新日期:2020-02-27
  • Hyperbolic Congruent Numbers
    Quaest. Math. (IF 0.619) Pub Date : 2020-01-23
    Injo Hur; Jang Hyun Jo

    We introduce the notion of hyperbolic congruent numbers which is a hyperbolic analogue of congruent numbers, and investigate the relations between congruent numbers and hyperbolic congruent numbers.

    更新日期:2020-01-23
  • The Golomb Topology of Polynomial Rings
    Quaest. Math. (IF 0.619) Pub Date : 2020-01-23
    Dario Spirito

    We study properties of the Golomb topology on polynomial rings over fields, in particular trying to determine conditions under which two such spaces are not homeomorphic. We show that if K is an algebraic extension of a finite field and K′ is a field of the same characteristic, then the Golomb spaces of K[X] and K′[X] are homeomorphic if and only if K and K′ are isomorphic.

    更新日期:2020-01-23
  • t-bargraphs and t-compositions
    Quaest. Math. (IF 0.619) Pub Date : 2019-12-02
    Toufik Mansour; Armend Sh. Shabani

    In this paper, we consider several statistics on t-compositions. We exhibit a bijection between the set of t-compositions and a set of bargraphs, introduced in this paper, named t-bargraphs. As our main statistic is per – the perimeter of a given t-bargraph, we obtain the corresponding generating function. We find both an explicit and an asymptotic formula for the total length of the perimeter over

    更新日期:2019-12-02
  • Profinite Cappitt groups
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-28
    A.L.P. Porto

    In this article we will give a characterization for the profinite Cappitt groups.

    更新日期:2019-11-28
  • Morita equivalence and Cauchy extensions of Hilbert C*-modules
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-28
    Kourosh Nourouzi; Ali Reza

    In this paper, we show that the Cauchy extensions of C*-algebras and Hilbert C*-modules preserve Morita equivalence of C*-algebras and Hilbert C*- modules, respectively. In particular, we show that the Cauchy extensions of Hilbert C*-modules preserve adjointable, unitary operators and partial isometries as well as full Hilbert C*-modules and linking algebras associated to Hilbert C*-modules.

    更新日期:2019-11-28
  • On the Alster, Menger and D-type covering properties
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-28
    Alexander V. Osipov; Selma Özçağ

    In this paper we give new characterizations for almost Menger and weakly Menger spaces by neighborhood assignments and define a natural weakening of almost D-spaces and weakly D-spaces. We discuss the relationships among the properties “D-type”, “Menger”, “Alster”, and the weak versions of these properties in Lindelöf spaces.

    更新日期:2019-11-28
  • Spectra of composition operators on Fock-type spaces
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-28
    Tesfa Mengestie; Werkaferahu Seyoum

    This work is a continuation of our recent investigation in [15] where we characterized various topological and dynamical properties of the composition operator Cψ acting between Fock-type spaces and when both exponents p and q are finite. Now we investigate the structures when at least one of the spaces is growth type and determine the spectrum of the operator Cψ on all the Banach spaces . The results

    更新日期:2019-11-28
  • Primal topologies on the integers
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-28
    S. García-Ferreira; A. Guale; J. Vielma

    Given an infinite set X and a function f : X → X, the primal topology on X induced by f is the topology τf = {U ⊆ X : f−1(U ) ⊆ U}. In this paper, we prove that there are 2ω pairwise non-homemomorphic primal topologies on ℕ. We also prove that an infinite set cannot have more than 2ω pairwise non-homeomorphic primal topologies. We give a necessary and sufficient condition to guarantee that an Alexandroff

    更新日期:2019-11-28
  • Alignments closed under a binary product
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-28
    Robert E. Jamison

    This paper is concerned with closure systems defined on groups such that the product of any two closed sets is again closed. The main objective of this paper is to show that if enough “small” subsets are closed, then all subsets are closed. It is shown that this is true for groups without any elements of order 2 provided all 2-element subsets are closed. The same holds for all Abelian groups with one

    更新日期:2019-11-28
  • Total Roman domination in digraphs
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-28
    Guoliang Hao; Wei Zhuang; Kangxiu Hu

    Let D be a finite and simple digraph with vertex set V (D). A Roman dominating function (RDF) on a digraph D is a function f : V (D) → {0, 1, 2} satisfying the condition that every vertex v with f (v) = 0 has an in-neighbor u with f (u) = 2. The weight of an RDF f is the value . An RDF f on D with no isolated vertex is called a total Roman dominating function if the subdigraph of D induced by the set

    更新日期:2019-11-28
  • Total Roman {2}-domination in graphs
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-28
    Suitberto Cabrera García; Abel Cabrera Martínez; Frank A. Hernández Mira; Ismael G. Yero

    Given a graph G = (V, E), a function f: V → {0, 1, 2} is a total Roman {2}-dominating function if every vertex ʋ ∈ V for which f (ʋ) = 0 satisfies that ∑u∈N (ʋ) f (ʋ) ≥ 2, where N (ʋ) represents the open neighborhood of ʋ, and every vertex x ∈ V for which f (x) ≥ 1 is adjacent to at least one vertex y ∈ V such that f (y) ≥ 1. The weight of the function f is defined as ω(f ) = ∑ʋ∈V f (ʋ). The total

    更新日期:2019-11-28
  • On the three questions of Bertram on locally maximal sum-free sets
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-28
    Chimere S. Anabanti

    We recently answered the three questions of Bertram in the finite abelian case in https://link.springer.com/article/10.1007/s00200-018-0364-0, Applicable Algebra in Engineering, Communication and Computing 30(2) (2019), 127–134. In this paper, we answer the nonabelian analogues of the three questions of Bertram on locally maximal sum-free sets.

    更新日期:2019-11-28
  • T-quasi continuous modules
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-28
    Parastoo Adhami; Javad Moghaderi; Adnan Tercan

    In this paper, we investigate the t-quasi continuous property for modules. It is proved that M is t-quasi continuous, if and only if M is a direct sum of a Z2-torsion module and a quasi-continuos module. Moreover we characterize the rings R for which certain R-modules are t-quasi continuous. We show that every R-module is t-quasi continuous, if and only if R(ℕ) is t-quasi continuous, if and only if

    更新日期:2019-11-28
  • Some expansions of functions based upon two sequences of hypergeometric polynomials
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-15
    Mohammad Masjed-Jamei; H.M. Srivastava

    In this paper, we introduce two series expansions whose basis functions are two sequences of hypergeometric polynomials. We then present a systematic and detailed study of the general properties of each of these series expansions. We consider several illustrative examples to show the computational efficiency of our expansions in comparison to the usual Taylor series expansion. We also discuss some

    更新日期:2019-11-15
  • On the cardinality of S(n)-Spaces
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-14
    Alexander V. Osipov

    In this paper, for a topological space X and any positive integer n, we define the cardinal functions sLθ(n) (X), θ(n)-quasi-Menger number qMθ(n) (X) and s(n)-quasi-Menger number qMs(n) (X). We prove the following statements: For every S(2n)-space X, |X| ≤ 2sL θ (n) (X) κθ (n) (X). For every S(2n)-space X, |X| ≤ 2qM θ (n) (X) κθ (n) (X). For every S(2n)-space X, |X| ≤ 2qM s (n) (X) κθ (n) (X). Similar

    更新日期:2019-11-14
  • Composite outer inverses for rectangular matrices
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-14
    Dijana Mosić; Predrag S. Stanimirović

    Various compositions of the Drazin inverse, the group inverse or the core-EP inverse with the Moore-Penrose inverse have investigated last years. Solving some type of matrix equations, we introduce three new generalized inverses of a rectangular matrix, which are called the OMP, MPO and MPOMP inverses, because the outer inverse and the Moore-Penrose inverse are incorporated in their definition. As

    更新日期:2019-11-14
  • On some probabilistic aspects of (generalized) dicyclic groups
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-14
    Mihai-Silviu Lazorec; Marius Tărnăuceanu

    In this paper we study probabilistic aspects, such as the subgroup commutativity degree and the cyclic subgroup commutativity degree, of (generalized) dicyclic groups. We find explicit formulas for these quantities and we provide another example of a class of groups whose (cyclic) subgroup commutativity degree vanishes asymptotically.

    更新日期:2019-11-14
  • About porosity of some Świątkowski functions in the space of quasi-continuous functions
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-14
    Gertruda Ivanova; Aleksandra Karasńska

    In the paper by M. Filipczak, G. Ivanova and J. Wódka, Comparison of some families of real functions in porosity terms, Math. Slovaca 67(5) (2017), 1155–1164, it was proved that the family of quasi-continuous Świątkowski functions is porous but not strongly porous in the space of quasi-continuous functions. We improved this result. We found the unique number q = 2/3 such that the family of quasi-continuous

    更新日期:2019-11-14
  • Domination versus semipaired domination in trees
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-14
    Wei Zhuang; Guoliang Hao

    In this paper, we study a parameter that is a relaxation of an important domination parameter, namely the paired domination. A set D of vertices in G is a semipaired dominating set of G if it is a dominating set of G and can be partitioned into 2-element subsets such that the vertices in each 2-set are at most distance two apart. The semipaired domination number, γpr2(G), is the minimum cardinality

    更新日期:2019-11-14
  • New congruences modulo 5 and 9 for partitions with odd parts distinct
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-14
    Houqing Fang; Fanggang Xue; Olivia X.M. Yao

    Let pod(n) denote the number of partitions of an integer n wherein the odd parts are distinct. Recently, a number of congruences for pod(n) have been established. In this paper, we establish the generating function of pod(5n + 2) and then prove new infinite families of congruences modulo 5 and 9 for pod(n) by using the formulas for t3(n) and t5(n), where tk (n) is the number of representations of n

    更新日期:2019-11-14
  • Existence and Stability of Solutions for Linear and Nonlinear Stieltjes Differential Equations
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-14
    Yu Chen; D. O’Regan; JinRong Wang

    This paper deals with Cauchy problems and nonlocal problems for non-linear Stieltjes differential equations corresponding to a certain function g. We establish existence and uniqueness results for nonlinear equations with initial value or nonlocal conditions in the space ℬ𝒞g ([0, H], ℝ) using fixed point methods and g-topology theory. We introduce the concepts of Ulam-Hyers (UH) and generalized Ulam-Hyers-Rassias

    更新日期:2019-11-14
  • A note on certain subrings of ℛ (L)
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-14
    Goutam Bhunia

    We introduce a new subring (L) of (L) for a completely regular frame L and characterize pseudocompact frames via these subrings. Also we obtain several sufficient conditions on L which guarantee that the cozero part of generates L. Further, we prove that the Stone-Čech compactification βL of L is determined by these subrings whenever L is pseudocompact or strongly zero-dimensional. Finally, we have conjectured

    更新日期:2019-11-14
  • On measure of noncompactness and application to global attractors of operator semigroups
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-14
    Ehmet Ablet; Xiaoling Chen; Lixin Cheng; Quanqing Fang; Zheming Zheng

    Based on the recent development of the theory of measures of noncompactness, we first show a representation theorem of measures of noncompactness defined on Banach spaces. Then, in terms of measure of noncompactness, we present some new characterizations of the existence of global attractors for norm-to-weak continuous semigroups, and a fixed point theorem for norm-to-weak continuous mappings.

    更新日期:2019-11-14
  • Ricci η-parallel trans-Sasakian 3-manifolds
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-07
    Yan Zhao

    In this paper, we present a new characterization for a trans-Sasakian 3-manifold to be proper. More precisely, we prove that if a compact trans-Sasakian 3-manifold has η-parallel Ricci operator, then the manifold is homothetic to a cosymplectic or a Sasakian 3-manifold or is of type (0, β) with ∇β = ξ(β)ξ.

    更新日期:2019-11-07
  • Metric dimensions of metric spaces over integers
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-07
    Yiming Lei

    We consider metric spaces over the ring of integers. For any generating set S of ℤ, it is shown that the metric dimension of the metric space X = X(ℤ, S) is not greater than 2 max S. The resolving set of metric space X = X(ℤ, S) is determined. If S = {−m, −(m − 1), . . . , −1, 1, . . . , m − 1, m}, then the metric dimension of the metric space X = X(ℤ, S) is m + 1. We determine the basis of the metric

    更新日期:2019-11-07
  • Multiplicative generalized Lie triple derivations on generalized matrix algebras
    Quaest. Math. (IF 0.619) Pub Date : 2019-11-07
    Aisha Jabeen

    Let be a commutative ring with unity, be -algebras, be ()-bimodule and be ()-bimodule. The -algebra is a generalized matrix algebra defined by the Morita context . In this article, we study multiplicative generalized Lie triple derivation on generalized matrix algebras and prove that every multiplicative generalized Lie triple derivation on a generalized matrix algebra has the standard form.

    更新日期:2019-11-07
  • A power of a combination of meromorphic function with its shift sharing small function with its derivative
    Quaest. Math. (IF 0.619) Pub Date : 2019-04-16
    Arup Dam; Sujoy Majumder

    In this paper, we use the idea of normal family to investigate the situation when a power of a combination of transcendental meromorphic function with its shift shares small function with it’s derivative and obtain three results which improve and generalize the recent result due to Lü and Yi [12]. Also we exhibit some examples to fortify the condition of our results.

    更新日期:2019-04-16
  • Generalized yamabe equations on riemannian manifolds and applications to Emden-Fowler problems
    Quaest. Math. (IF 0.619) Pub Date : 2019-03-25
    David Barilla; Giuseppe Caristi; Shapour Heidarkhani; Shahin Moradi

    In this paper, we establish the existence of solutions and multiplicity properties for generalized Yamabe equations on Riemannian manifolds. Problems of this type arise in conformal Riemannian geometry, astrophysics, and in the theories of thermionic emission, isothermal stationary gas sphere, and gas combustion. The abstract results of this paper are illustrated with Emden-Fowler equations involving

    更新日期:2019-03-25
  • Separation axioms and covering dimension of asymmetric normed spaces
    Quaest. Math. (IF 0.619) Pub Date : 2019-03-20
    Victor Donjuán; Natalia Jonard-Pérez

    It is well known that every asymmetric normed space is a T0 paratopological group. Since all Ti axioms (i = 0, 1, 2, 3) are pairwise non-equivalent in the class of paratopological groups, it is natural to ask if some of these axioms are equivalent in the class of asymmetric normed spaces. In this paper, we will consider this question. We will also show some topological properties of asymmetric normed

    更新日期:2019-03-20
  • Robustly measure expansiveness for C1 vector fields
    Quaest. Math. (IF 0.619) Pub Date : 2019-03-19
    Manseob Lee

    Let X be a C1 vector field of a compact connected boundaryless smooth smooth Riemannian manifold M with dimM ≥ 3. We show the following: (i) if the chain recurrence set 𝓡(X) is robustly measure expansive, then it is Axiom A without cycles; and (ii) if the homoclinic class H(Orb(p), X) that contains a hyperbolic periodic orbit Orb(p) is generic-robustly measure expansive, then it is hyperbolic.

    更新日期:2019-03-19
  • Certain new factor theorems for infinite series and trigonometric fourier series
    Quaest. Math. (IF 0.619) Pub Date : 2019-03-19
    Hüseyin Bor

    In this paper, firstly we proved a general theorem dealing with absolute Riesz summability factors of infinite series under weaker conditions. And secondly we applied it to the trigonometric Fourier series. Also we have obtained some new and known results.

    更新日期:2019-03-19
  • Contractible Köthe co-echelon algebras
    Quaest. Math. (IF 0.619) Pub Date : 2019-03-18
    Krzysztof Piszczek

    In this note we investigate contractibility properties in the class of the so-called DF-algebras. We also give a complete characterization of contractible Köthe co-echelon algebras.

    更新日期:2019-03-18
  • On the pointwise multipliers of the space BMOA
    Quaest. Math. (IF 0.619) Pub Date : 2019-03-17
    Miroljub Jevtić; Boban Karapetrović

    In this note we present a new characterization of the pointwise multipliers of the space BMOA.

    更新日期:2019-03-17
  • Binary codes and partial permutation decoding sets from biadjacency matrices of bipartite graphs Γ(2k, k, k + 1, 1)
    Quaest. Math. (IF 0.619) Pub Date : 2019-03-17
    W. Fish; N.B. Mumba; E. Mwambene; B.G. Rodrigues

    For a set Ω = {1, 2, . . . , n} where n = 2k ≥ 6, let Ω{k} denote the set of all subsets of Ω of size k. We examine the binary codes from the row span of biadjacency matrices of bipartite graphs with bipartition (Ω{k}, Ω{k+1}) and two vertices as k-subsets and (k+1)-subsets of Ω being adjacent if they have one element in common. We show that S2k is contained in the automorphism group of the graphs

    更新日期:2019-03-17
  • Investigation of the eigenvalues and root functions of the boundary value problem together with a transmission matrix
    Quaest. Math. (IF 0.619) Pub Date : 2019-03-17
    Ekin Uğurlu

    In this paper, we consider a singular even-order Hamiltonian system on the union of two intervals together with appropriate boundary and transmission conditions. For investigating the spectral properties of the problem we pass to the inverse operator with an explicit form and we prove some completeness theorems.

    更新日期:2019-03-17
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