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 Subjects -> MATHEMATICS (Total: 1051 journals)     - APPLIED MATHEMATICS (85 journals)    - GEOMETRY AND TOPOLOGY (23 journals)    - MATHEMATICS (775 journals)    - MATHEMATICS (GENERAL) (43 journals)    - NUMERICAL ANALYSIS (23 journals)    - PROBABILITIES AND MATH STATISTICS (102 journals) MATHEMATICS (775 journals)                  1 2 3 4 | Last

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 Afrika MatematikaJournal Prestige (SJR): 0.235 Number of Followers: 1      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1012-9405 - ISSN (Online) 2190-7668 Published by Springer-Verlag  [2570 journals]
• On retraction problem concerning inclusion of F -contractions in almost
contractions
• Abstract: Abstract We have established, in the context of metric spaces, that an F-contraction restricted to appropriate neighborhood of its fixed point is an almost contraction and obtain definition of retractions on complete metric spaces. We have illustrated such an inclusion using an example studied in Wardowski (Fixed Point Theory Appl 94:1–6, 2012) and in Minak et al. (Bull Belg Math Soc Simon Stevin 22:411–422, 2015).
PubDate: 2019-03-15

• Existence of weak and renormalized solutions of degenerated elliptic
equation
• Abstract: Abstract We consider the degenerate nonlinear elliptic equation (E) : $${\mathcal {A}}(u)= g-{\text {div}}(f)$$ , where $${\mathcal {A}}(u)=-{\text {div}}(a(x,u,\nabla u))$$ is a Leray-Lions operator defined on $$W_0^{1,p(\cdot )}(\Omega )$$ allowed to be non linear degenerated. The main gaol of this paper is to prove in first, an $$L^{\infty }(\Omega )$$ estimate for the bounded solution of (E), and then the existence of a weak and a renormalized solution of (E), with $$f\in (L^{r(\cdot )}(\Omega ))^N, g\in L^{q(\cdot )}(\Omega )$$ , where $$r(\cdot )$$ and $$q(\cdot )$$ satisfies the following conditions : \begin{aligned} {\left\{ \begin{array}{ll} r(x)>\frac{N}{p(x)-1}, r(x)\ge p'(x)&{}\quad \forall x \in \Omega ,\\ q(x)>\max \left( \frac{N}{p(x)},1\right) , q(x)\ge p'(x)&{}\quad \forall x \in \Omega . \end{array}\right. } \end{aligned}
PubDate: 2019-03-14

• Two-phase quasi-Newton method for unconstrained optimization problem
• Abstract: Abstract In this paper, a two-phase quasi-Newton scheme is proposed for solving an unconstrained optimization problem. The global convergence property of the scheme is provided under mild assumptions. The superlinear convergence rate of the scheme is also proved in the vicinity of the solution. The advantages of the proposed scheme over the traditional schemes are justified with numerical table and graphical illustrations.
PubDate: 2019-03-12

• A new iterative method for finding the multiple roots of nonlinear
equations
• Abstract: Abstract In this paper, an iterative method for multiple roots of nonlinear equations is presented. Its convergence order is analyzed and proved. It is shown that the proposed method has third-order convergence. To assess the validity and performance of the proposed method, some nonlinear equations are solved and the results are compared with the results from six other methods.
PubDate: 2019-03-11

• Some fixed point theorems for $$S_F$$ S F -contraction in complete fuzzy
metric spaces
• Abstract: Abstract In this paper, we prove some fixed point theorems by introducing a new F-contraction namely $$S_F$$ -contraction in fuzzy metric spaces by combining the idea of Wardowski’s (Fixed Point Theory Appl 2012, Article ID 94, 2012) and Secelean’s (Fixed Point Theory Appl 2013, Article ID 277, 2013) contractions in metric spaces and Grabiec’s (Fuzzy Sets Syst 125, 385–389, 1988) contraction in fuzzy metric spaces. An example is also given to support the results proved herein.
PubDate: 2019-03-08

• An efficient conjugate gradient trust-region approach for systems of
nonlinear equation
• Abstract: Abstract In this paper, we introduce a combination of family of some conjugate gradient methods (CG) with the trust-region method. Whenever the trust-region algorithm is unsuccessful, a family of CG methods is used to prevent resolving the trust-region subproblem. The computational cost for such a family is trivial. The global theory of the new approach is proved and numerical experiments are reported.
PubDate: 2019-03-08

• A duopoly preemption game with two alternative stochastic investment
choices
• Abstract: Abstract This paper studies a duopoly investment model with uncertainty. There are two alternative irreversible investments. The first firm to invest gets a monopoly benefit for a specified period of time. The second firm to invest gets information based on what happens with the first investor, as well as cost reduction benefits. We describe the payoff functions for both the leader and follower firm. Then, we present a stochastic control game where the firms can choose when to invest, and hence influence whether they become the leader or the follower. In order to solve this problem, we combine techniques from optimal stopping and game theory. For a specific choice of parametres, we show that no pure symmetric subgame perfect Nash equilibrium exists. However, an asymmetric equilibrium is characterized. In this equilibrium, two disjoint intervals of market demand level give rise to preemptive investment behavior of the firms, while the firms otherwise are more reluctant to be the first mover.
PubDate: 2019-03-07

• Ricci soliton and geometrical structure in a perfect fluid spacetime with
torse-forming vector field
• Abstract: Abstract In this paper geometrical aspects of perfect fluid spacetime with torse-forming vector field $$\xi$$ are described and Ricci soliton in perfect fluid spacetime with torse-forming vector field $$\xi$$ are determined. Conditions for the Ricci soliton to be expanding, steady or shrinking are also given.
PubDate: 2019-03-07

• Some inequalities in relation with Fekete–Szegö problems specified by
the Hadamard products of certain meromorphically analytic functions in the
punctured unit disc
• Abstract: Abstract In this investigation, in the light of the q-derivative operator and the q-analog of the well-known generalized Bessel function, several inequalities relating to Fekete–Szegö problems specified by the Hadamard product of certain meromorphic functions analytic in the punctured unit disc are first achieved and some consequences of them are then pointed out.
PubDate: 2019-03-07

• On a problem of George Andrews concerning partitions with even parts below
odd parts
• Abstract: Abstract Recently, George Andrews gave a detailed study of partitions with even parts below odd parts in which only the largest even part appears an odd number of times. In this note, we provide a combinatorial proof of a generating function identity related to such partitions. This answers a problem of Andrews.
PubDate: 2019-03-06

• Predictable representation for time inhomogeneous Lévy processes and
BSDEs
• Abstract: Abstract The aim of this paper is to give the predictable representation property associated with Lévy process in the non-homogeneous case. In this latter, we establish the existence and uniqueness of solution for the Backward Stochastic Differential Equations and its relation with Partial integro-differential equations.
PubDate: 2019-03-05

• One point compactification of generalized topological spaces
• Abstract: Abstract The notions of a s- $$T_1$$ space, an almost generalized Hausdorff space, and a $$\mu$$ -locally compact space in the context of generalized topological spaces are introduced. Properties in relation to these spaces are established. Finally, a version of one point compactification of a s- $$T_1$$ space is obtained.
PubDate: 2019-03-01

• Specht polynomials and modules over the Weyl algebra
• Abstract: Abstract In this paper we study the decomposition structure of a direct image of a polynomial ring under certain map.
PubDate: 2019-03-01

• Necessary and sufficient conditions for hypergeometric functions to be in
a subclass of analytic functions
• Abstract: Abstract In the present paper, we determine necessary and sufficient conditions for zF(a, b; c; z) and $$z(2-F(a,b;c;z))$$ where $$F(a,b;c;z)=\sum \nolimits _{n=0}^{\infty }[(a)_{n}(b)_{n}/(c)_{n}(1)_{n}]z^{n}$$ to be in a certain class of analytic functions with negative coefficients. Furthermore, we consider an integral operator related to hypergeometric functions.
PubDate: 2019-03-01

• Fully discrete approximation of general nonlinear Sobolev equations
• Abstract: We consider abstract quasilinear evolution equations of Sobolev type in a Hilbert setting. We propose two fully discrete schemes and prove some error estimates under minimal assumptions. Various examples that enter into our abstract framework are considered, for each of them our theoretical results are confirmed by several numerical experiments.
PubDate: 2019-03-01

• On the Janowski class of generalized Struve functions
• Abstract: Abstract In this paper, we are mainly interested to find the sufficient conditions on parameters A, B, b and c that will ensure the generalized Struve function $$u_{v,b,c}$$ satisfies the subordination $$u_{v,b,c}\left( z\right) \prec \left( 1+Az\right) /\left( 1+Bz\right)$$ .
PubDate: 2019-03-01

• Operators and multipliers on weighted Bergman spaces
• Abstract: Abstract In 1992, Blasco considered a weighted Bergman space using Dini-weight function. He proved that a linear operator T on weighted Bergman space to any Banach space X is bounded if and only if certain one parameter fractional derivative of a single X-valued analytic function satisfy some growth condition. In this paper, we use a three parameters fractional derivative of a single X-valued analytic function and provide an equivalent condition. Our technique uses the Gaussian hypergeometric functions. Furthermore we supply some conditions on the parameters a, b and c under which the Gaussian hypergeometric functions F(a, b; c; z) are Dini-weight.
PubDate: 2019-03-01

• Positive integer solutions of some Diophantine equations in terms of
integer sequences
• Abstract: Abstract In this paper, we define some new number sequences, which we represent as $$(B_{n}),(b_{n}),(y_{n})$$ and present relations of these new sequences with each other. Then, we give all positive integer solutions of some Diophantine equations in terms of these new sequences.
PubDate: 2019-03-01

• Proximity structure on generalized topological spaces
• Abstract: Abstract The aim of the present article is to introduce a kind of proximity structure, termed $$\mu$$ -proximity, on a set X, which ultimately gives rise to a generalized topology on the ambient set X. An alternative description of $$\mu$$ -proximity is given and it is shown that any generalized topology of a generalized topological space $$(X, \mu )$$ is always induced by a suitable $$\mu$$ -proximity if and only if $$(X, \mu )$$ satisfies a type of complete regularity condition. The notion of quasi $$\mu$$ -proximity is also introduced and the desired result that every generalized topology can be achieved from a quasi $$\mu$$ -proximity, is proved.
PubDate: 2019-03-01

• On hyperlattices: congruence relations, ideals and homomorphism
• Abstract: Abstract We introduce the notion of congruences in hyperlattices. We prove that a quotient of a hyperlattice by a congruence is a “weak-hyperlattice” and not a hyperlattice in general. We explore the connections between congruences, ideals and homomorphism of hyperlattices. In particular, we establish necessary and sufficient conditions for a zero-congruence class to be an ideal of a hyperlattice.
PubDate: 2019-03-01

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