Showing papers in "Filomat in 2015"

A New Approach to the Study of Fixed Point Theory for Simulation Functions

Abstract: Let (X; d) be a metric space and T : X! X be a mapping. In this work, we introduce the mapping : (0;1) (0;1)! R, called the simulation function and the notion ofZ-contraction with respect to which generalize the Banach contraction principle and unify several known types of contractions involving the combination of d(Tx; Ty) and d(x; y): The related fixed point theorems are also proved.

Coefficient Bounds for a Certain Class of Analytic and Bi-Univalent Functions

Abstract: In this paper, we introduce and investigate a subclass of analytic and bi-univalent functions in the open unit disk $\mathbb{U}$ . By using the Faber polynomial expansions, we obtain upper bounds for the coefficients of functions belonging to this analytic and bi-univalent function class. Some interesting recent developments involving other subclasses of analytic and bi-univalent functions are also briefly mentioned.

Some inequalities on submanifolds in statistical manifolds of constant curvature

Abstract: In this paper, we study the behaviour of submanifolds in statistical manifolds of constant curvature. We investigate curvature properties of such submanifolds. Some inequalities for submanifolds with any codimension and hypersurfaces of statistical manifolds of constant curvature are also established.

Initial Coefficient Bounds for a General Class of Bi-Univalent Functions

Abstract: Recently, Srivastava et al. [22] reviewed the study of coefficient problems for bi-univalent functions. Inspired by the pioneering work of Srivastava et al. [22], there has been triggering interest to study the coefficient problems for the different subclasses of bi-univalent functions (see, for example, [1, 3, 6, 7, 27, 29],). Motivated essentially by the aforementioned works, in this paper we propose to investigate the coefficient estimates for a general class of analytic and bi-univalent functions. Also, we obtain estimates on the coefficients |a2| and |a3| for functions in this new class. Further, we discuss some interesting remarks, corollaries and applications of the results presented here.

Resolvent Operator and Spectrum of New Type Boundary Value Problems

Abstract: The aim of this study is to investigate a new type boundary value problems which consist of the equation $-y''(x) + (\mathcal{B}y)(x) = \lambda y(x)$ on two disjoint intervals $(-1 , 0) \ \textrm{and} \ (0 , 1)$ together with transmission conditions at the point of interaction $x = 0$ and with eigenparameter dependent boundary conditions, where $\mathcal{B}$ is an abstract linear operator. By suggesting an own approaches we introduce modified Hilbert space and linear operator in it such a way that the considered problem can be interpreted as an eigenvalue problem of this operator. We establish such properties as isomorphism and coerciveness with respect to spectral parameter, maximal decreasing of the resolvent operator and discreteness of the spectrum. Further we examine asymptotic behaviour of the eigenvalues.

Curvature properties of some class of minimal hypersurfaces in Euclidean spaces

Abstract: We determine curvature properties of pseudosymmetry type of some class of minimal 2-quasiumbilical hypersurfaces in Euclidean spaces En+1, n ≥ 4. We present examples of such hypersurfaces. The obtained results are used to determine curvature properties of biharmonic hypersurfaces with three distinct principal curvatures in E5. Those hypersurfaces were recently investigated by Y. Fu in [38].

Generalized fractional Hermite-Hadamard inequalities for twice differentiable s-convex functions

Abstract: Some Hermite-Hadamard type inequalities via Riemann-Liouville fractional integral for twice differentiable functions having some s-convexity of second kind properties are established. A class of s-affne of second kind functions is identifed such as these inequalities are sharp.

Anti-Invariant Riemannian Submersions from Cosymplectic Manifolds onto Riemannian Manifolds

Abstract: We introduce anti-invariant Riemannian submersions from cosymplectic manifolds onto Riemannian manifolds. We survey main results of anti-invariant Riemannian submersions defined on cosymplectic manifolds. We investigate necessary and sufficient condition for an anti-invariant Riemannian submersion to be totally geodesic and harmonic. We give examples of anti-invariant submersions such that characteristic vector field ξ is vertical or horizontal. Moreover we give decomposition theorems by using the existence of anti-invariant Riemannian submersions.

Variations on quasi-Cauchy sequences

Abstract: In this paper, we introduce and study new kinds of continuities. It turns out that a function f defined on an interval is uniformly continuous if and only if there exists a positive integer p such that f preserves p-quasi-Cauchy sequences where a sequence (xn) is called p-quasi-Cauchy if the sequence of differences between p-successive terms tends to 0.

Best Proximity Point and Best Proximity Coupled Point in a Complete Metric Space with (P)-Property

Abstract: In this paper, we utilize the concept of (P)-property, weak (P)-property and the comparison function to introduce and prove an existence and uniqueness theorem of a best proximity point. Also, we introduce the notion of a best proximity coupled point of a mapping F : X X! X. Using this notion and the comparison function to prove an existence and uniqueness theorem of a best proximity coupled point. Our results extend and improve many existing results in the literature. Finally, we introduce examples to support our theorems.

Monodromy groupoid of an internal groupoid in topological groups with operations

Abstract: In this paper, the internal groupoid structure of the monodromy groupoid for topological internal groupoids is developed.

An application of multicriteria group decision making by soft covering based rough sets

Abstract: In this work we define soft covering based rough set and present its related properties. Also we present an example in medicine which aims to find the patients with high prostate cancer risk. Our datas are 56 patients from Selcuk University Meram Medicine Faculty.

Upward and downward statistical continuities

Abstract: A real valued function $f$ defined on a subset $E$ of $\mathbb{R}$, the set of real numbers, is statistically upward continuous if it preserves statistically upward half quasi-Cauchy sequences, is statistically downward continuous if it preserves statistically downward half quasi-Cauchy sequences; and a subset $E$ of $\mathbb{R}$, is statistically upward compact if any sequence of points in $E$ has a statistically upward half quasi-Cauchy subsequence, is statistically downward compact if any sequence of points in $E$ has a statistically downward half quasi-Cauchy subsequence where a sequence $(x_{n})$ of points in $\mathbb{R}$ is called statistically upward half quasi-Cauchy if \[ \lim_{n\rightarrow\infty}\frac{1}{n}|\{k\leq n: x_{k}-x_{k+1}\geq \varepsilon\}|=0 \] is statistically downward half quasi-Cauchy if \[ \lim_{n\rightarrow\infty}\frac{1}{n}|\{k\leq n: x_{k+1}-x_{k}\geq \varepsilon\}|=0 \] for every $\varepsilon>0$. We investigate statistically upward continuity, statistically downward continuity, statistically upward half compactness, statistically downward half compactness and prove interesting theorems. It turns out that any statistically upward continuous function on a below bounded subset of $\mathbb{R}$ is uniformly continuous, and any statistically downward continuous function on an above bounded subset of $\mathbb{R}$ is uniformly continuous.

Turán type inequalities for generalized inverse trigonometric functions

Abstract: In this paper we study the inverse of the eigenfunction sinp of the one-dimensional p-Laplace operator and its dependence on the parameter p, and we present a Turan type inequality for this function. Similar inequalities are given also for other generalized inverse trigonometric and hyperbolic functions. In particular, we deduce a Turan type inequality for a series considered by Ramanujan, involving the digamma function

A prey-predator model with infection in both prey and predator

Abstract: This paper aims to study the dynamical behaviours of a prey-predator system where both prey and predator populations are affected by diseases. A system of four differential equation has been proposed and analyzed. Stability of the equilibrium points of the model has been investigated. Computer simulations are carried out to illustrate our analytical findings. The biological implications of analytical and numerical findings are discussed critically.

A Generalization of Ćirić Fixed Point Theorems

Abstract: In this paper, we state and prove a generalization of \'Ciri\'c fixed point theorems in metric space by using a new generalized quasi-contractive map. These theorems extend other well known fundamental metrical fixed point theorems in the literature (Banach \cite{SB1922}, Kannan \cite{RK1968}, Nadler \cite{SBN1969}, Reich \cite{SR1972}, etc.) Moreover, a multi-valued version for generalized quasi-contraction is also established.

Soft intersection semigroups, ideals and bi-ideals; a new application on semigroup theory I

Abstract: In this paper, we dene soft intersection semigroups, soft intersection left (right, two-sided) ideals and bi-ideals of semigroups, give their properties and interrelations and we characterize regular, intra-regular, completely regular, weakly regular and quasi-regular semigroups in terms of these ideals.

Generalized frames with c*-valued bounds and their operator duals

Abstract: ‎Certain facts about frames and generalized frames are extended for the new g-frames‎, ‎referred as‎ *-g-frames‎, ‎in a Hilbert C*-modules‎. ‎As a matter of fact‎, ‎some relations are establish‎ ‎between *-frames and *-g-frames in a Hilbert C*-module‎. ‎Furthermore‎, ‎the paper studies‎ the operators associated to a given *-g-frame‎, ‎the construction of new *-g-frames‎. ‎Moreover‎, ‎the operator duals for a *-g-frame are introduced and‎ ‎their properties are investigated‎. ‎Finally‎, ‎operator duals of a *-g-frame are characterized‎.

On the Structure Tensors of Almost Contact B-Metric Manifolds

Abstract: The space of the structure (0,3)-tensors of the covariant derivatives of the structure endomorphism and the metric on almost contact B-metric manifolds is considered. A known decomposition of this space in orthogonal and invariant subspaces with respect to the action of the structure group is used. We determine the corresponding components of the structure tensor and consider the case of the lowest dimension 3 of the studied manifolds. Some examples are commented.

Estimation of stress-strength reliability using record ranked set sampling scheme from the exponential distribution

Abstract: ‎In this paper‎, ‎point and interval estimation of stress-strength reliability based on upper record ranked set sampling (RRSS) from one-parameter exponential distribution are considered‎. ‎Maximum likelihood estimator (MLE) as well as the uniformly minimum variance unbiased estimator (UMVUE) of stress-strength parameter are derived and their performance are studied‎. ‎Also‎, ‎some confidence intervals for stress-strength reliability based on upper RRSS are constructed and then compared on the basis of a simulation study‎. ‎Finally‎, ‎a data set has been analyzed for illustrative purposes‎.

Fuzzy soft games

Abstract: In this work, after given the definition of fuzzy soft sets and their basic operations we define two person fuzzy soft games which can apply to problems contain vagueness and uncertainty. We then give different four solution methods of the games which are fuzzy soft saddle points, fuzzy soft lover and upper values, fuzzy soft dominated strategies and fuzzy soft Nash equilibrium. We also give a probabilistic equilibrium solution method for the two persons fuzzy soft games (tpfs-games) which show that every finite tpfs$-game with probabilistic strategies has one solution. Finally, we give an application which shows that the methods can be successfully applied to a financial problem and extended the two person fuzzy soft games to n-person fuzzy soft games.

F-geodesics on manifolds

Abstract: The notion of F-geodesic, which is slightly different from that of F-planar curve (see [14], [15]), generalizes the magnetic curves, and implicitly the geodesics, by using any (1,1)-tensor field on the manifold (in particular the electro-magnetic field or the Lorentz force). We give several examples of F-geodesics and the characterizations of the F-geodesics w.r.t. Vranceanu connections on foliated manifolds and adapted connections on almost contact manifolds. We generalize the classical projective transformation, holomorphic-projective transformation and C-projective transformation, by considering a pair of symmetric connections which have the same F-geodesics. We deal with the transformation between such two connections, called F-projective transformation. We obtain a Weyl type tensor field, invariant under any F-projective transformation, on a 1-codimensional foliation.

Infinite Matrices and Almost Convergence

Abstract: In the present paper, we characterize $\left( {r^q(u,p):\,f_\infty } \right)$, $\left( {r^q(u,p):\,f } \right)$ and $\left( {r^q(u,p):\,f_0 } \right)$; where $f_{\infty},~f$ and $f_0$ denotes, respectively, the spaces of almost bounded sequences, almost convergent sequences and almost sequences converging to zero, where the space $r^q(u,p)$ of non-absolute type have recently been introduced by Neyaz and Hamid (see, [12]).

Further discussion on modified multivalued α*-ψ-contractive type mapping

Abstract: In this paper, we investigate the existence of a fixed point for modified multivalued α*-ψ-contractive type mapping in the context of complete metric space. We also construct some examples to illustrate the main result. Our results extend, improve and generalize the results on the topic in the literature.

Classification of Quasi-Sum Production Functions with Allen Determinants

Abstract: In this paper, we derive an explicit formula for the determinant of Allen’s matrix of quasi-sum production functions. We completely classify the quasi-sum production functions by using their Allen determinants. Further, we give some geometric applications of Allen determinants.

Some Cosmological Solutions of a Nonlocal Modified Gravity

Abstract: We consider nonlocal modification of the Einstein theory of gravity in framework of the pseudo-Riemannian geometry. The nonlocal term has the form $\mathcal{H}(R) \mathcal{F}(\Box)\mathcal {G}(R)$, where $\HH$ and $\GG$ are differentiable functions of the scalar curvature $R,$ and $ \mathcal{F}(\Box)= \displaystyle \sum_{n =0}^{\infty} f_{n}\Box^{n}$ is an analytic function of the d'Alambert operator $\Box .$ Using calculus of variations of the action functional, we derived the corresponding equations of motion. The variation of action is induced by variation of the gravitational field, which is the metric tensor $g_{\mu u}$. Cosmological solutions are found for the case when the Ricci scalar $R$ is constant.

Majorization and Doubly Stochastic Operators

Abstract: We present a close relationship between row, column and doubly stochastic operators and the majorization relation on a Banach space lp(I), where I is an arbitrary non-empty set and p \in [1,\infty]. Using majorization, we point out necessary and sufficient conditions that an operator D is doubly stochastic. Also, we prove that if P and P−1 are both doubly stochastic then P is a permutation. In the second part we extend the notion of majorization between doubly stochastic operators on lp(I), p \in [1,\infty), and consider relations between this concept and the majorization on lp(I) mentioned above. Moreover, we give conditions that generalized Kakutani’s conjecture is true.

On Modified Srivastava-Gupta Operators

Abstract: Very recently the modied form of Srivastava-Gupta operators was studied in order to preserve the linear functions. Here, we estimate the rate of approximation for functions having bounded derivatives of the modied form.

Extremal topological indices for graphs of given connectivity

Abstract: In this paper, we show that in the class of graphs of order n and given (vertex or edge) connectivity equal to k (or at most equal to k), 1 = 1. Also, for 2-connected (or 2-edge connected) graphs and \alpha > 0 the unique graph minimizing these indices is the n-vertex cycle Cn.

The Lower Bound for the Modulus of the Derivatives and Jacobian of Harmonic Injective Mappings

Abstract: We give the lower bound for the modulus of the radial derivatives and Jacobian of harmonic injective mappings from the unit ball onto convex domain in plane and space. As an application we show co-Lipschitz property of some classes of qch mappings. We also review related results in planar case using some novelty. Throughout the paper we denote by , G and D open subset of R n , n> 1. Let B n (x; r) =fz2 R n :jz xj < rg; S n 1 (x; r) = @B n (x; r) (abbreviated S(x; r)) and let B n ; S = S n 1 stand for the unit ball and the unit sphere in R n , respectively. In particular, by D we denote the unit disc B 2 and T =@D we denote the unit circle S 1 in the complex plane. For a domain D in R n with non-empty boundary, we define the distance function d = dD = dist(D) by d(x) = d(x;@D) = dist(D)(x) = inffjx yj : y2 @Dg; and if f maps D onto D 0 R n , in some settings it is convenient to use short notation d = d (x) = d f (x) for d( f (x);@D 0 ). It is clear that d(x) = dist(x; D c ), where D c is the complement of D in R n . Let G be an open set in R n . A mapping f : G! R m is di erentiable at x2 G if there is a linear mapping f 0 (x) : R n ! R n , called the derivative of f at x, such that f (x + h) f (x) = f 0 (x)h +jhj"(x; h) where"(x; h)! 0 as h! 0. For a vector-valued function f : G! R n , where G R n , is a domain, we define j f 0 (x)j = max jhj=1 j f 0 (x)hj and l( f 0 (x)) = min jhj=1 j f 0 (x)hj;