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Shifting powers in Spivey’s Bell number formula Quaest. Math. (IF 1.049) Pub Date : 2020-12-05 Toufik Mansour; Reza Rastegar; Alexander Roitershtein; Mark Shattuck
Abstract In this paper, we consider extensions of Spivey’s Bell number formula wherein the argument of the polynomial factor is translated by an arbitrary amount. This idea is applied more generally to the r-Whitney numbers of the second kind, denoted by W (n, k), where some new identities are found by means of algebraic and combinatorial arguments. The former makes use of infinite series manipulations
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On Salem half-norms Quaest. Math. (IF 1.049) Pub Date : 2020-12-02 Toufik Zaïmi
Abstract Let α be a Salem number with conjugates , where α 1 := α. We prove some properties of the products of the form α 1 α 2 · · · αn, called, by A. Dubickas and C.J. Smyth, Salem half-norms. This allows us to complete, partially, two related results due to C. Christopoulos and J. McKee about the Galois group of the splitting field of the minimal polynomial of α, and to A. Dubickas on a question
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Star partial order in indefinite inner product spaces Quaest. Math. (IF 1.049) Pub Date : 2020-12-02 Ivana M. Stanišev
Abstract We define the star partial order for matrices in spaces with an indefinite inner product. We also give a characterization of that order in terms of matrices and their Moore-Penrose inverses. Finally, some interesting properties are shown.
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On the Bounded Sets in Cc (X) Quaest. Math. (IF 1.049) Pub Date : 2020-12-02 Lahbib Oubbi
Abstract If X is Hausdorff topological space and Cc (X) is the topological algebra obtained by endowing the algebra C(X) of all continuous functions on X with the topology τc of uniform convergence on the compact subsets of X, then the set Δ(ϕ) := {g ∈ C(X) : |g(x)| ≤ ϕ(x), x ∈ X} is bounded in Cc (X), for every non-negative ϕ ∈ C(X). In this note we deal with the question whether the collection C
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Covering dimension and ideal topological spaces Quaest. Math. (IF 1.049) Pub Date : 2020-12-02 A.C. Megaritis
Abstract In this paper we study dimensions of the type dim for the class of ideal topological spaces. We shall start from the classical definition of the dimension functions dim and dim*, continue with the dimension -dim and finally, give two different kinds of functions of covering dimensional type.
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On the p -regular G-conjugacy classes with sizes 1 or minimal Quaest. Math. (IF 1.049) Pub Date : 2020-12-02 Xianhe Zhao; Yanyan Zhou; Ruifang Chen; Qin Huang
Abstract Let N be a p-solvable normal subgroup of a finite group G, and Np′ be a p′ -Hall subgroup of N . If x is an element of G, then the conjugacy class size |xG| = |G : CG(x)|. Obviously, when CG(x) is a maximal subgroup of G, |xG| is minimal. In this paper, we investigate the structure of Np′ by assuming that |xG | is 1 or minimal for every p-regular element x of N
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Certain properties of Jordan homomorphisms, n-Jordan homomorphisms and n-homomorphisms on rings and banach algebras Quaest. Math. (IF 1.049) Pub Date : 2020-12-02 Taher Ghasemi Honary
Abstract We investigate under what conditions n-Jordan homomorphisms between rings are n-homomorphism, or homomorphism; and under what conditions, n-Jordan homomorphisms are continuous. One of the main goals in this work is to show that every n-Jordan homomorphism f : A → B, from a unital ring A into a ring B with characteristic greater than n, is a multiple of a Jordan homomorphism and hence, it is
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On irreducible denumerable continuous parameter circuit chains: Analysis of a generalized sample path case Quaest. Math. (IF 1.049) Pub Date : 2020-12-02 Chrysoula V. Ganatsiou
Abstract By using the cycle-circuit representation theory of Markov processes we investigate the continuous parameter analogue of the existence and construction of a class of irreducible, denumerable Markov chains generated by a collection of overlapping directed weighted circuits regarding a generalized sample path case.
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A second type of higher order generalized geometric polynomials and higher order generalized Euler polynomials Quaest. Math. (IF 1.049) Pub Date : 2020-12-02 Cristina B. Corcino; Roberto B. Corcino; Bayram Çekim; Levent Kargin; Sithembele Nkonkobe
Abstract In this study we introduce a second type of higher order generalized geometric polynomials. This we achieve by examining the generalized stirling numbers S(n, k, α, β, γ) [Hsu and Shiue, 1998] for some negative arguments. We study their number theoretic properties, asymptotic properties, and their combinatorial properties using the notion of barred preferential arrangements. We also proposed
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Blow up of solutions for a nonlinear viscoelastic system with general source term Quaest. Math. (IF 1.049) Pub Date : 2020-12-02 Salah Boulaaras; Youcef Bouizem
Abstract This work studies the blow up result of the solution of a coupled nonlocal singular viscoelastic equation with general source terms under some suitable conditions. This work is a natural continuation to the previous recent article in ([4]).
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Almost η-Ricci and Almost η-Yamabe Solitons with Torse-Forming Potential Vector Field Quaest. Math. (IF 1.049) Pub Date : 2020-12-02 Adara M. Blaga; Cihan Özgür
Abstract We provide properties of almost η-Ricci and almost η-Yamabe solitons on submanifolds isometrically immersed into a Riemannian manifold whose potential vector field is the tangential component of a torse-forming vector field on , treating also the case of a minimal or pseudo quasi-umbilical hypersurface. Moreover, we give necessary and sufficient conditions for an orientable hypersurface of the
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On a type of superlinear growth variational problems Quaest. Math. (IF 1.049) Pub Date : 2020-10-22 Zhi Wang; Xiangfeng Yang
Abstract In this note, we propose an elementary method to study the existence and uniqueness of solutions to a type of variational problems which arise naturally in the theory of large deviations. This type of problems involves a movable boundary and may not have the coercivity condition in general. Our method is elementarily based on direct analysis over the space of absolutely continuous functions
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Topological connectednesses and congruences Quaest. Math. (IF 1.049) Pub Date : 2020-10-21 Stefan Veldsman
Abstract It is known that the connectednesses of topological spaces in the sense of Preuß is the topological analogue of the Kurosh-Amistsur radicals of algebraic structures in a categorical sense. Here this connection is further explored. As in universal algebra, a congruence on a topological space has been defined. It is shown that a connectedness can be characterized in terms of conditions on congruences
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On the product of primal spaces Quaest. Math. (IF 1.049) Pub Date : 2020-10-19 Othman Echi
Abstract Let X be a set and f : X → X be a map. We denote by 𝒫(f) the topology defined on X whose closed sets are the subsets A of X with f (A) ⊆ A. A topology on X is said to be a primal topology, if it is a 𝒫(f) for some map f. Our aim here is to characterize when the product of an arbitrary family of topological spaces is a primal space.
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Double outer-independent domination number of graphs Quaest. Math. (IF 1.049) Pub Date : 2020-10-19 Abel Cabrera Martínez
Abstract Let G be a graph with no isolated vertex. A set D ⊆ V(G) is a double outer-independent dominating set of G if V (G) \ D is an independent set and | N[υ] ∩ D| ≥ 2 for every v ϵ V(G), where N[υ] denotes the closed neighbourhood of v. The minimum cardinality among all double outer-independent dominating sets of G is the double outer-independent domination number of G. In this paper, we continue
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Weighted inner inverse for rectangular matrices Quaest. Math. (IF 1.049) Pub Date : 2020-10-19 Ratikanta Behera; Dijana Mosić; Jajati Kesahri Sahoo; Predrag S. Stanimirović
Abstract. To extend the notation of inner inverses, we define weighted inner inverses of a rectangular matrix. In particular, we introduce a W -weighted (B, C)-inner inverse of A, for given matrices A, W, B, C, and present some characterizations and conditions for its existence. Since this new inverse is not unique, we describe the set of all W -weighted (B, C)-inner inverses of a given matrix. Several
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Durrmeyer variant of apostol-genocchi-baskakov operators Quaest. Math. (IF 1.049) Pub Date : 2020-10-19 Naokant Deo; Sandeep Kumar
Abstract We study the approximation behavior of the Durrmeyer form of Apostol- Genocchi polynomials with Baskakov type operators including K-functional and second-order modulus of smoothness, Lipschitz space and find the rate of convergence for continuous functions whose derivative satisfies the condition of bounded variation. In the last section, we estimate weighted approximation behavior for these
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Matrix characterization of asymptotically deferred equivalent sequences Quaest. Math. (IF 1.049) Pub Date : 2020-10-19 Rabia Savaş
Abstract In 1932 Agnew [1] introduced the concept of deferred Ceśaro means. Taking inspiration from this new approach, in this paper we introduce deferred asymptotically equivalent sequences using statistical convergence and prove some important results. This will be accomplished through a series of regularity type theorems.
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On the product of primal spaces Quaest. Math. (IF 1.049) Pub Date : 2020-10-19 Othman Echi
Abstract Let X be a set and f : X → X be a map. We denote by 𝒫(f) the topology defined on X whose closed sets are the subsets A of X with f (A) ⊆ A. A topology on X is said to be a primal topology, if it is a 𝒫(f) for some map f. Our aim here is to characterize when the product of an arbitrary family of topological spaces is a primal space.
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The powers of two as sums over partitions Quaest. Math. (IF 1.049) Pub Date : 2020-10-16 Mircea Merca
Abstract In this paper, we investigate two methods to express the natural powers of 2 as sums over integer partitions. First we consider a formula by N. J. Fine that allows us to express a binomial coefficient in terms of multinomial coefficients as a sum over partitions. The second method invokes the central binomial coefficients and the logarithmic differentiation of their generating function. Some experimental
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Multivalued generalized graphic θ-contraction on directed graphs and application to mixed volterra-fredholm integral inclusion equations Quaest. Math. (IF 1.049) Pub Date : 2020-10-16 Lakshmi Kanta Dey; Hiranmoy Garai; Hemant Kumar Nashine; Can Huu Nguyen
Abstract The purpose of the present work is to introduce a generalized graphic θ-contraction conditions on a family of mappings defined on subsets of a metric space endowed with a set-transitive directed graph, and discuss common fixed point results without considering any kind of commutativity and continuity of the family of mappings. Useful examples illustrate the applicability and effectiveness of
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Quadratic model updating for damped gyroscopic systems Quaest. Math. (IF 1.049) Pub Date : 2020-10-14 Yongxin Yuan
Abstract This paper is concerned with the problem of the optimal approximation for a given matrix pencil (Ma, Da, Ga, Ka, Na ) under the spectral constraint and the symmetric constraint. Such a problem arises in finite element model updating for damped gyroscopic systems. By using constrained optimization theory and matrix derivatives, an explicit formulation for the solution of the problem is established
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Notes on star covering properties Quaest. Math. (IF 1.049) Pub Date : 2020-10-14 Yan-Kui Song; Wei-Feng Xuan
Abstract In this paper, we show the following statements: (1) There exists a pseudocompact star Lindelöf Tychonoff space which is not star σ-compact. (2) There exists a Tychonoff pseudocompact star countable (hence, star Lindelöf) space having a pseudocompact, Gδ regular closed subspace which is not star Lindelöf. (3) Assuming , there exists a normal star countable (hence, star Lindelöf) space having
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Frame congruences via subkernels Quaest. Math. (IF 1.049) Pub Date : 2020-10-14 Halimeh Moghbeli
Abstract To study the quotient of algebras, like frames, whose algebraic structures are determined by a partial order, it is often more common to think about sub-kernels of homomorphisms between such algebras. So, in this paper, we first introduce the concept of a pre-congruence on a frame and then characterize them as the sub-kernels of the frame homomorphisms. Second, we characterize the frame congruences
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Joint discrete universality for periodic zeta-functions. III Quaest. Math. (IF 1.049) Pub Date : 2020-10-14 Antanas Laurinčikas
Abstract In the paper, a joint theorem on the approximation of collections of analytic functions by generalized discrete shifts of zeta-functions with periodic coefficients is obtained. The latter result extend theorems of [9].
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A two-variable dirichlet series and its applications Quaest. Math. (IF 1.049) Pub Date : 2020-10-14 Mehmet Cenkci; Abdurrahman Ünal
Abstract We define a two-variable Dirichlet series associated with two arithmetic functions, which is related to the Riemann zeta function, the Dirichlet L-function, the Dirichlet series associated to the harmonic numbers, and truncated multiple zeta functions. Using the periodic Euler-Maclaurin summation formula, we obtain a representation in terms of an ordinary Dirichlet series, which leads to the
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On Rall's 1/2-conjecture on the domination game Quaest. Math. (IF 1.049) Pub Date : 2020-10-14 Csilla Bujtás; Vesna Iršič; Sandi Klavžar; Kexiang Xu
Abstract The 1/2-conjecture on the domination game asserts that if G is a traceable graph, then the game domination number γg (G) of G is at most A traceable graph is a 1/2-graph if holds. It is proved that the so-called hatted cycles are 1/2-graphs and that unicyclic graphs fulfill the 1/2-conjecture. Several additional families of graphs that support the conjecture are determined and computer experiments
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k−Fibonacci numbers close to a power of 2 Quaest. Math. (IF 1.049) Pub Date : 2020-10-14 Jhon J. Bravo; Carlos A. Gómez; Jose L. Herrera
Abstract A generalization of the well-known Fibonacci sequence is the k-generalized Fibonacci sequence whose first k terms are 0, . . . , 0, 1 and each term afterwards is the sum of the preceding k terms. In this paper, by using a lower bound to linear forms in logarithms of algebraic numbers due to Matveev and some argument of the theory of continued fractions, we find all the members of F (k) which
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On a power-type coupled system of k-hessian equations Quaest. Math. (IF 1.049) Pub Date : 2020-10-08 Chenghua Gao; Xingyue He; Maojun Ran
Abstract We deal with a coupled system of k-Hessian equations: where k = 1, 2, · · · , N , B is a unit ball in ℝ N , N ≥ 2, α and β are positive constants. By using the fixed-point index theory in cone, we obtain the existence, uniqueness and nonexistence of radial convex solutions for some suitable constants α and β. Furthermore, by using a generalized Krein-Rutman theorem, we also obtain a necessary
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Partially ordered objects in a topos Quaest. Math. (IF 1.049) Pub Date : 2020-09-29 A. Homayoun Nejah; Mojgan Mahmoudi; M. Mehdi Ebrahimi
Abstract In this paper we study the category of partially ordered objects in a topos E . The definition of a partially ordered object or internal poset is taken from [10], ϵ. Mac Lane and I. Moerdijk, Sheaves in geometry and logic, 1992. We will define the concept of monotone morphism between internal posets and then study the resulting category. We will show that the category of partially ordered
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Symmetry analysis for a fourth-order noise-reduction partial differential equation Quaest. Math. (IF 1.049) Pub Date : 2020-09-29 P.G.L. Leach; Andronikos Paliathanasis
Abstract We apply the theory of Lie symmetries in order to study a fourth-order 1+2 evolutionary partial differential equation which has been proposed for the image processing noise reduction. In particular we determine the Lie point symmetries for the specific 1+2 partial differential equations and we apply the invariant functions to determine similarity solutions. For the static solutions we observe
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Biderivations and linear commuting maps on the restricted contact lie algebras K(n; ) Quaest. Math. (IF 1.049) Pub Date : 2020-09-23 Yuan Chang; Liangyun Chen; Xin Zhou
Let K be the restricted contact Lie algebras K(n, ) over an algebraically closed field F of characteristic p > 3. We prove that each skew-symmetric biderivation of K is inner and show that commuting maps on K are scalar multiplication maps. Moreover, it is showed that the commuting automorphisms and dertivations of K are proved to be the identity mappings and zero mappings, respectively. Meanwhile
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Spacetimes admitting the Z-symmetric tensor Quaest. Math. (IF 1.049) Pub Date : 2020-09-22 Füsun Özen Zengin; Ayşe Yavuz Taşci
This paper aims to introduce the spacetimes admitting the Z-symmetric tensor. We investigate the properties of these spacetimes for a perfect fluid and a pressureless perfect fluid (a dust). Some theorems about the properties are proved.
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A representation of continuous lattices based on closure spaces Quaest. Math. (IF 1.049) Pub Date : 2020-09-22 Qingguo Li; Longchun Wang; Lingjuan Yao
In this paper, we establish the link between continuous lattices and closure spaces. By generalizing the notion of algebraic closure space to continuous closure space, we show that continuous lattices can be represented by continuous closure spaces, just as algebraic lattices can be represented by algebraic closure spaces. We also introduce the notion of approximable mappings between continuous closure
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On poly-Bell numbers and polynomials Quaest. Math. (IF 1.049) Pub Date : 2020-09-22 Ghania Guettai; Diffalah Laissaoui; Mourad Rahmani; Madjid Sebaoui
This paper aims to construct a new family of numbers and polynomials which are related to the Bell numbers and polynomials by means of the confluent hypergeometric function. We give various properties of these numbers and polynomials (generating functions, explicit formulas, integral representations, recurrence relations, probabilistic representation, …). We also derive some combinatorial sums including
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Paths in primal spaces and the Collatz conjecture Quaest. Math. (IF 1.049) Pub Date : 2020-09-22 Angel Guale; Fernando Mejias; Jorge Vielma
The Collatz conjecture establishes that for every natural number n ∈ ℕ, there exists an r ∈ ℕ such that κr (n) = 1, where κ : ℕ → ℕ is the function defined as n/2 if n es even and as 3n + 1 if n is odd. The map κ induces a topology τκ on ℕ. We prove that the Collatz conjecture and connectedness of the space (ℕ, τκ ) imply that the space is simply connected. Furthermore, we prove that the Collatz conjecture
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A new transcendental number from the digits of NN Quaest. Math. (IF 1.049) Pub Date : 2020-09-22 Hùng Việt Chu
We first give a summary of the history of transcendental numbers, and then we use a nice technique by G. Dresden to find a new transcendental number. In particular, while previous work looked at the last non-zero digit of nn , we consider the digit immediately before its last non-zero digit and show that the infinite decimal built from these digits is transcendental.
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The riesz tensor product of d-algebras Quaest. Math. (IF 1.049) Pub Date : 2020-09-22 Mohamed Amine Ben Amor
In this work we prove that the Riesz tensor product of two archimedean d-algebras is again a d-algebra.
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A Zariski topology on integrally closed maximal subrings of a commutative ring Quaest. Math. (IF 1.049) Pub Date : 2020-09-22 Alborz Azarang
Abstract Let R be a commutative ring and Xi.c (R) denotes the set of all integrally closed maximal subrings of R. It is shown that if R is a non-field G-domain, then there exists S ∈ Xi.c (R) with (S : R) = 0. If K is an algebraically closed field which is not absolutely algebraic, then we prove that the polynomial ring K[X] has an integrally closed maximal subring with zero conductor too; a characterization
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Permanence for Leslie-Gower predator-prey system with feedback controls on time scales Quaest. Math. (IF 1.049) Pub Date : 2020-08-25 Zhouhong Li; Tianwei Zhang
A novel feedback control of Leslie-Gower system on time scales is proposed in this paper. By using the time scale calculus theory, the permanence of the model is studied. Further, the influences of the feedback controls on the upper and lower bounds of prey and predator populations are also discussed. The work of this paper improves some research findings in recent years. Some illustrative examples
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Almost quasi-Yamabe solitons and gradient almost quasi-yamabe solitons in paracontact geometry Quaest. Math. (IF 1.049) Pub Date : 2020-08-25 Krishnendu De; Uday Chand De
The purpose of the present paper is to investigate the almost quasi- Yamabe soliton and gradient almost quasi-Yamabe solitons under the framework of three-dimensional normal almost paracontact metric manifolds.
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Reducibility sets for sequences of matrices Quaest. Math. (IF 1.049) Pub Date : 2020-08-25 Luis Barreira; Claudia Valls
Our main aim is to give a complete characterization of the reducibility sets of continuous 1-parameter families of sequences of matrices, which turn out to be the Fσ -sets. We also show that for any Fσ -set containing zero, one can find a family with this reducibility set. In addition, we obtain corresponding results for the reducibility-stability set and we give an optimal condition for the reducibility
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On the continuity of the adjoint of evolution operators Quaest. Math. (IF 1.049) Pub Date : 2020-08-25 Diómedes Bárcenas; Bladismir Leal; Hugo Leiva; Ambrosio Tineo Moya
By associating a quasi semigroup to a commutative evolution operator and using techniques from vector measures like the Gel’fand integral and the Radon- Nikodym theorem for Bochner integral, we prove the continuity on [0, +∞) of the adjoint of a certain class of evolution operators. Furthermore, we provide examples of evolution operators satisfying our conclusion. We also provide an application to
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Uniformly graded-coherent rings Quaest. Math. (IF 1.049) Pub Date : 2020-08-25 Chahrazade Bakkari; Najib Mahdou; Abdelkbir Riffi
Let be a ring graded by an arbitrary grading abelian group Γ. We say that R is a uniformly graded-coherent ring if there is a map ϕ : ℕ → ℕ such that for every n ∈ ℕ, and any nonzero graded R-module homomorphism of degree 0, where λ 1 , … ,λn are degrees in Γ, ker f can be generated by ϕ(n) homogeneous elements. In this paper, we provide the elementary properties of uniformly graded-coherent rings
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Approximate properties of the p-Bieberbach polynomials in regions with simultaneously exterior and interior zero angles Quaest. Math. (IF 1.049) Pub Date : 2020-08-25 F.G. Abdullayev; M. Imashkyzy; P. Özkartepe
In this paper, we study the uniform convergence of p-Bieberbach polynomials in regions with a finite number of both interior and exterior zero angles at the boundary.
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Inequalities about normalized Lp projection body Quaest. Math. (IF 1.049) Pub Date : 2020-08-25 Zhongwen Tang; Lin Si
In this paper, we establish a Loomis-Whitney type inequality about volume normalized Lp projection body for p ≥ 1 with complete equality conditions for p ̸= 2. Meanwhile, an estimate for the weighted Lp zonoid is given.
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On the lower Lie nilpotency index of a group algebra Quaest. Math. (IF 1.049) Pub Date : 2020-08-25 Meena Sahai; Bhagwat Sharan
In this article, we show that if KG is a Lie nilpotent group algebra of a group G over a field K of characteristic p > 0, then tL (KG) = k if and only if tL (KG) = k, for k ∈ {5p − 3, 6p − 4}, where tL (KG) and tL (KG) are the lower and the upper Lie nilpotency indices of KG, respectively.
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Corrigendum Quaest. Math. (IF 1.049) Pub Date : 2020-08-25
(2020). Corrigendum. Quaestiones Mathematicae. Ahead of Print.
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On global values of virtual waiting time of a customer in open queueing networks Quaest. Math. (IF 1.049) Pub Date : 2020-08-25 Saulius Minkevičius; Leonidas L. Sakalauskas
The object of this research on queueing theory is to analyze the behaviour of open queueing network, working under overload heavy traffic conditions. We have proved probability limit theorem for the global values of virtual waiting time of a customer in open queueing networks. Finally, we present application of the recurrent method in the further analysis of open queuing networks.
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Moving front solutions of a time-fractional power-law fluid under gravity Quaest. Math. (IF 1.049) Pub Date : 2020-08-25 Sameerah Jamal; Nkosingiphile Mnguni
This paper considers a fractional-order, incompressible power-law fluid on a horizontal plane, where the time component is defined by Riemann-Liouville derivatives. The model is characterized by a nonlinear second-order partial differential equation comprising of a power-law parameter β. We transform the model into nonlinear fractional ordinary differential equations and subsequently, solutions of
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Pseudo core inverses of a sum of morphisms Quaest. Math. (IF 1.049) Pub Date : 2020-08-25 Jianlong Chen; Wende Li; Mengmeng Zhou
Let be an additive category with an involution ∗. Suppose that both ϕ : X → X is a morphism of with pseudo core inverse ϕ and η : X → X is a morphism of such that 1 + ϕ η is invertible. Let α = (1 + ϕ η) − 1 , β = (1+ηϕ ) − 1 , ε = (1−ϕϕ )ηα(1−ϕ ϕ), γ = α(1−ϕ ϕ)ηϕ β, σ = αϕ ϕα− 1(1− ϕϕ )β, δ = β∗ (ϕ ) ∗η∗ (1−ϕϕ )β. Then we present a sufficient condition such that f = ϕ + η − ε has pseudo core inverse
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Two types of Galois correspondences over quantaloid-typed sets Quaest. Math. (IF 1.049) Pub Date : 2020-07-15 Jinming Fang; Zhou Fang
For a small, integral and meet-continuous quantaloid , we establish two types of Galois correspondences by considering a limit structure on a set as a -multiple limit structure on a -typed set. One Galois correspondence shows that the stratified -topologies and the -multiple limit structures based on -typed sets can be converted to each other categorically. Moreover, the other one shows that a new
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General multiplicative Zagreb indices of trees with given independence number Quaest. Math. (IF 1.049) Pub Date : 2020-07-15 Selvaraj Balachandran; Tomáš Vetrík
We obtain lower and upper bounds on general multiplicative Zagreb indices for trees with given independence number and order. Bounds on basic multiplicative Zagreb indices follow from our results. We also show that the bounds are best possible.
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Lower topological algebraic domain models of topological spaces Quaest. Math. (IF 1.049) Pub Date : 2020-07-13 Hui Li; Qingguo Li
The maximal point space of a domain (resp. algebraic domain) with the Scott topology is Choquet complete. Thus, not every T 1 topological space can be represented as the maximal point space of some algebraic domain equipped with the Scott topology. However, in this paper, we prove that: (1) Every T 1 topological space is homeomorphic to the set of all maximal points of some algebraic domain equipped
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Multiply warped products with compact Einstein manifolds Quaest. Math. (IF 1.049) Pub Date : 2020-07-13 Fatma Karaca
We study multiply warped products with compact Einstein manifolds. We obtain that there does not exist connected, compact Einstein multiply warped products if the scalar curvature is non-positive. It is also found that there does not exist non-trivial connected Einstein multiply warped product manifolds with compact base or compact fibres.
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A new factor theorem on generalized absolute Cesàro summability Quaest. Math. (IF 1.049) Pub Date : 2020-07-13 Hüseyin Bor
In this paper, we have proved a general theorem dealing with the ϕ −| C, α, β |k summability factors of infinite series. Also, some new and known results are deduced.
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On some new Gaussian hypergeometric summation formulae with applications Quaest. Math. (IF 1.049) Pub Date : 2020-07-13 Insuk Kim; T.K. Pogány; Arjun K. Rathie
The aim of this note is to provide some new Gaussian hypergeometric summation formulae. These are further used to obtain certain new expressions for the product of hypergeometric series. Already obtained results by Bailey, Choi and Rathie and Qureshi et al. follow special cases of our main findings.
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On equivalence of absolute double weighted mean methods Quaest. Math. (IF 1.049) Pub Date : 2020-07-13 Mehmet Ali Sarigöl
Bor [1], Bor and Thorpe [2] and the author [8] established the set of necessary and sufficient condition for the equivalence of absolute weighted mean summability methods of infinite series. In the present paper we extend their result to doubly infinite series by two dimensional weighted mean, which also includes the result of Rhoades [7].
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Einstein type tensors in the generalized Riemannian space Quaest. Math. (IF 1.049) Pub Date : 2020-07-13 Vladislava M. Stanković
In [22], V.M. Stankovíc introduced generalized Einstein type tensors of the kind θ (θ = 1, 2) in the generalized Riemannian space, and some relations which they satisfy are obtained using the first and the second kind of covariant derivative. In the present paper, generalized Einstein type tensors of the kind θ (θ = 3, 4) are introduced. Also, some relations which Einstein type tensors of the kind
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Positioned numerical semigroups Quaest. Math. (IF 1.049) Pub Date : 2020-07-13 M.B. Branco; M.C. Faria; J.C. Rosales
A numerical semigroup S is positioned if for all s ∈ ℕ\S we have that F(S) + m(S) − s ∈ S. In this paper, we give algorithms to compute the set of positioned semigroups and a criterium to check whether S is or not is positioned. Furthermore, we prove the Wilf’s conjecture for this type of numerical semigroups.
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