Search

In this paper, we will consider the coupled fixed point problem for single-valued operators satisfying a symmetric contraction condition with respect to maximum. An application to a periodic boundary value problem illustrates the results. The study of a coupled coincidence problem is also suggested. [ABSTRACT FROM AUTHOR]

We say that over an arbitrary ring a module M has the property (WE) (respectively, (WEE) if M has a weak supplement (respectively, ample weak supplements) in every extension. In this paper, we provide various properties of modules with these properties. We show that a module M has the property (WEE) iff every submodule of M has the property (WE). A ring R is left perfect iff every left R-module has the property (WE) iff every left R-module has the property (WEE). A ring R is semilocal iff every left R-module has a weak supplement in every extension with small radical. We also study modules that have a weak supplement(respectively, ample weak supplements) in every coatomic extension, namely the property. (WE*)(respectively, (WEE*). [ABSTRACT FROM AUTHOR]

A quadratic stochastic operator (in short QSO) is usually used to present the time evolution of differing species in biology. Some quadratic stochastic operators have been studied by Lotka and Volterra. In the present paper, we first give a simple characterization of Volterra QSO in terms of absolutely continuity of discrete measures. Moreover, we provide its generalization in continuous setting. Further, we introduce a notion of orthogonal preserving QSO, and describe such kind of operators defined on two dimensional simplex. It turns out that orthogonal preserving QSOs are permutations of Volterra QSO. The associativity of genetic algebras generated by orthogonal preserving QSO is studied too. [ABSTRACT FROM AUTHOR]

An ideal I of a commutative ring R is said to be irreducible if it cannot be written as the intersection of two larger ideals. A proper ideal I of a ring R is said to be strongly irreducible if for each ideals J, K of R, J ∩ K ⊆ I implies that J ⊆ I or K ⊆ I. In this paper, we introduce the concepts of 2-irreducible and strongly 2-irreducible ideals which are generalizations of irreducible and strongly irreducible ideals, respectively. We say that a proper ideal I of a ring R is 2-irreducible if for each ideals J, K and L of R, I = J ∩K ∩L implies that either I = J ∩K or I = J ∩L or I = K∩L. A proper ideal I of a ring R is called strongly 2-irreducible if for each ideals J, K and L of R, J ∩K ∩L ⊆ I implies that either J ∩K ⊆ I or J ∩L ⊆ I or K ∩L ⊆ I. [ABSTRACT FROM AUTHOR]

S. Radeleczki in 2002 raised the open problem of the characterization of those atomistic complete lattices whose classification lattices are geometric. This paper solves the problem for the finite cases. [ABSTRACT FROM AUTHOR]

In this paper we obtain a condition for the tangent bundle(TM,J,ḡ) to be locally decomposable Golden Riemannian tangent bundle, where JQ is the Golden structure on TM and ḡ is the Cheeger-Gromoll metric. [ABSTRACT FROM AUTHOR]

In this paper, we introduce the notion of generalized weakly α-contractive mappings and give some common fixed point results for this type of contraction. The presented theorems extend, generalize and improve many existing results in the literature. Two examples as well as an application to ordinary differential equations are also given in order to illustrate the effectiveness of the obtained results. [ABSTRACT FROM AUTHOR]

The main purpose of this paper is to study the existence of solutions of stochastic subdifferential inclusions systems driven by standard Brownian motion. We first use the subjectivity theorem to obtain the existence result of subdifferential inclusion, and then, by applying the Banach contraction principle we obtain the solution of the corresponding stochastic system. Our results are inspired by the one in which the existence and uniqueness of solutions to the subdifferential inclusion system is given. [ABSTRACT FROM AUTHOR]

In recent years, differential inclusions with fractional order have been extensively studied by many authors. However, up to now fractional evolution inclusions with Riemann- Liouville derivative have not been considered in the literature. In order to fill this gap, in this paper we establish sufficient conditions for the existence of solutions of fractional evolution inclusions involving the Riemann-Liouville fractional derivative. The cases of convex-valued and nonconvex-valued right-hand sides are considered and we present a version of Filippov's theorem for fractional semilinear differential inclusions with Riemann-Liouville derivative. [ABSTRACT FROM AUTHOR]

Let R be a commutative Noetherian regular local ring containing a field. Let I be an ideal of R and let l ≥ 0 be an integer. In this paper it is shown that for every finitely generated R-module M and each integer i ≥l the Bass numbers of the R-module HIi(M) are finite, whenever, dimSupp(HIi(R)) ≤ 1, for all i ≥ l. [ABSTRACT FROM AUTHOR]

The main aim of this paper is the investigation of the stability problem for ordinary delay differential equations. More precisely, we would like to study the following problem. Assume that for a continuous function a given delay differential equation is fulfilled only approximately. Is it true that in this case this function is close to an exact solution of this delay differential equation?. [ABSTRACT FROM AUTHOR]

Recently, a new definition of fractional derivative called as the conformable fractional derivative which based on limits introduced by Khalil et al (2014). Later, Abdeljawad (2015) improved these definitions and gave the basic concepts in this new fractional calculus. In this paper, we generalize Abel's formula and Wronskian determinant definition and establish existence and uniqueness theorems for sequential linear conformable fractional differential equations. [ABSTRACT FROM AUTHOR]

The paper is focused on the numerical investigation of the Navier-Stokes equation applying a spectral method. A MATLAB code is developed and used for simulation. The incompressible two-dimensional flow in a square container called lid-driven cavity is tested as a benchmark problem. The streamlines, the horizontal and vertical velocity components at different Reynolds numbers are presented. There is significant agreement with the numerical results and those published in the literature. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the global stability of a virus infection model with humoral immune response and distributed intracellular delays. The incidence rate of infection is given by general functional response. The model has two types of distributed time delays which describe the time needed for infection of uninfected cell and virus replication. Lyapunov functionals are constructed and LaSalle's invariance principle is used to establish the global asymptotic stability of all steady states of the model. We have proven that, if the basic reproduction number R0 is less than or equal unity, then the uninfected steady state is globally asymptotically stable (GAS), and if the humoral immune response reproduction number R1 is less than or equal unity and R0 > 1, then the infected steady state without humoral immune response exists and it is GAS, and if R1 > 1, then the infected steady state with humoral immune response exists and it is GAS. Numerical simulations have been carried out with a specific form of the incidence rate function. We have shown that, both the numerical and theoretical results are consistent. [ABSTRACT FROM AUTHOR]

We know that every terraced matrix has the factorization Rb=DbC, where C is the Cesàro matrix and Db= diag{(n+1)bn}. In the present paper, we define the generalized terraced matrix by using the generalized Cesàro matrix in the expression above, and some properties of this matrix are given. [ABSTRACT FROM AUTHOR]

The paper is about calculating multiple fractional part integrals of the form ...where {x} denotes the fractional part of x and k,m and p are nonnegative integers. We show that these integrals can be expressed as series involving products of Riemann zeta function values and some binomial coefficients. We obtain, as particular cases of our results, new integral representations of Euler's constant as double and triple symmetric fractional part integrals. [ABSTRACT FROM AUTHOR]

The generalized bi-periodic Fibonacci sequence f{qn}∞n=0 have initial conditions q0=0, q1 = 1 and recurrence relation qn = qn-1 + qn-2 (when n is even and n ≥ 2) or qn = bqn-1 + qn-2 (when n is odd and n ≥ 3), where a and b are nonzero real numbers. Some well-known sequences, such as the Fibonacci sequence, the Pell sequence and the k-Fibonacci sequence, are special cases of this generalization. In this paper, we consider the partial infinite sum derived from the reciprocal of the generalized bi-periodic Fibonacci numbers. [ABSTRACT FROM AUTHOR]

Using a method proposed by T.A. Burton in [6] and Banach's Contraction Principle, we study the existence, uniqueness and approximation of the solution for a bilocal problem. We compare our results with the classical similarly results given for the Fredholm integral operator associated. The present paper extends and complements the results from [14]. [ABSTRACT FROM AUTHOR]

In this paper, we introduce and investigate a new subclass HΣh,p (λ;O) of analytic and bi-univalent functions in the open unit disk U: For functions belonging to this class, we obtain estimates on the first two Taylor-Maclaurin coefficients |a2| and |a3|. [ABSTRACT FROM AUTHOR]

Let D be a finite and simple digraph with vertex set V(D). A twin Roman dominating function (TRDF) on D is a labeling f W V(D) → {0,1,2}g such that every vertex with label 0 has an in-neighbor and out-neighbor with label 2. The weight of a TRDF f is the value w(f)= ΣvεV(D) f (v). The twin Roman domination number of a digraph D, denoted by γR(D), equals the minimum weight of a TRDF on D. In this paper we initiate the study of the twin Roman domination number in digraphs. In particular, we present sharp bounds for γR(D) and determine the exact value of the twin Roman domination number for some classes of digraphs. [ABSTRACT FROM AUTHOR]

This paper is concerned with the existence of solutions for initial value problems of functional and neutral functional Hadamard type fractional differential inclusions. We apply appropriate fixed point theorems for multivalued maps to obtain the existence results for the given problems covering convex as well as non-convex cases. Some illustrative examples are also presented. [ABSTRACT FROM AUTHOR]

Let R be a semiprime ring with center Z(R). A mapping F: R→ R is called a generalized derivation if there exists a derivation d : R→R such that F(xy) = F(x)y+xd(y) holds for all x,yϵR. In the present paper, our main object is to study the situations: (1) F(xy)-F(x)F (y)ϵ Z(R), (2) F(xy)+F(x)F(y)ϵ Z(R), (3) F(xy)-F(y)F(x) ϵ Z(R), (4) F(xy)+F(y)F(x) ϵ Z(R); for all x,y in some suitable subset of R. [ABSTRACT FROM AUTHOR]

One of the outstanding problems in combinatorial design theory is concerning the existence of 2-(v,k, 1) designs. In particular, the existence of 2-(v,k, 1) designs admitting an interesting group of automorphisms is of great interest. Thirty years ago, a six-person team classified 2-(v,k, 1) designs which have flag-transitive automorphism groups. Since then the effort has been to classify those 2-(v,k, 1) designs which are block-transitive but not flagtransitive. This paper is a contribution to this program and we prove there is nonexistence of 2-(v,k, 1) designs admitting a point-primitive block-transitive but not flag-transitive automorphism group G with socle Eg(q). [ABSTRACT FROM AUTHOR]

In this paper we propose a new collocation type method for solving Volterra integral equations of the second kind with weakly singular kernels. In this method we use the complex Bspline basics in collocation method for solving Volterra integral. We compare the results obtained by this method with exact solution. A few numerical examples are presented to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, our approach allows to refine the results announced by Ebadian et al. [Results Math., 36 (2013), 409-423]. Namely, we reduce the distance between approximate and exact double derivations on Banach algebras and Lie C*-algebras up to 1/2n-1 and 1/2n-2 for n⩾2. Indeed, we give a correct utilization of fixed point theory in the sense of Diaz and Margolis [Bull. Amer. Math. Soc., 74 (1968), 305-309] concerning the stability of double derivations. [ABSTRACT FROM AUTHOR]

In this paper, the existence of solution for generalized equilibrium problems under compactness or non-compactness assumptions in abstract convex spaces is proved. The closedness and the convexity of the solution set are also obtained. Our results generalize and improve some recent results in the literature. [ABSTRACT FROM AUTHOR]

This paper is devoted to finding explicit formulas for two kinds of reproducing kernels in some reproducing kernel spaces. Usually for calculating the reproducing kernel of space Wm2 [a;b], one must solve a large system of ordinary differential equations with 4m equations in 4m unknowns. Hence, it is worthy to have explicit formulas to save time and computational efforts. The advantage of using these formulas is clearly seen in the plotted graphs. [ABSTRACT FROM AUTHOR]

The object of the present paper is to prove the existence of a generalized quasi Einstein spacetime, briefly G(QE)4, by constructing a non-trivial Lorentzian metric and to study such spacetime. First, we prove that every W2-Ricci pseudosymmetric G(QE)4 is an N(k)-quasi Einstein spacetime which can be considered as a model of perfect fluid, in general relativity. Then, we consider Ricci symmetric G(QE)4 and we prove that in such spacetime satisfying Einstein's field equations, the energy density and the isotropic pressure are constants. As a consequence of this result, the expansion scalar and the acceleration vector vanish and also the possible local cosmological structures of this spacetime obeying Einstein's field equations are of Petrov I, D or O. [ABSTRACT FROM AUTHOR]

In this paper two modifications of Kolchin's generalized allocation scheme are studied. Results known for Kolchin's scheme are extended to the new models. Representation theorems, strong laws of large numbers and local limit theorems are obtained. In the proofs some general inequalities are used. [ABSTRACT FROM AUTHOR]

The paper introduces some sets of double lacunary invariant sequences defined by four dimensional RH-regular matrices and Orlicz functions. First we study some basic properties of such sets by equipping them with linear topological structure. Further, we investigate some relationships among such sets under different conditions and finally compare with a set of double lacunary statistically convergent sequences. [ABSTRACT FROM AUTHOR]

The first geometric-arithmetic index GA1(G), which was introduced by D. Vukiċević and B. Furtula recently, is a graph-based molecular structure descriptor. The aim of this paper is to obtain new inequalities involving the geometric-arithmetic index GA1 and other well known topological indices. In particular, we relate the geometric-arithmetic index of a graph G with its first Zagreb index M1(G), its second Zagreb index M2(G), its modified Zagreb index Z-1(G) and its Randić index R(G). [ABSTRACT FROM AUTHOR]

In this paper, we have given a criteria for the existence of common fixed point for pair of mappings in 2-metric spaces and establish common fixed point theorems for certain class of contractive type mappings. The results presented here, generalize some well known fixed point theorems given in the literature. [ABSTRACT FROM AUTHOR]

The functional defined as the difference of the right-hand and the left-hand side of Jensen's inequality is called Jensen's functional. The aim of this paper is to study its lower bounds. More precisely, some refinements of its lower bounds are recaptured under more relaxed conditions on the n-tuple x. [ABSTRACT FROM AUTHOR]

In this paper we establish some Tauberian-like conditions in terms of the weighted general control modulo of integer order to retrieve subsequential convergence of a sequence from its boundedness. [ABSTRACT FROM AUTHOR]

In this paper, the consimilarity of complex matrices is generalized for commutative quaternion matrices. In this regard, the coneigenvalue and coneigenvector for commutative quaternion matrices are defined. Also, the existence of solution to the some commutative quaternion matrix equations is characterized and solutions of these matrix equations are derived by means of real representations of commutative quaternion matrices. [ABSTRACT FROM AUTHOR]

In this paper, we will show Tauberian conditions under which λstatistical convergence follows from (V,λ)-statistical convergence. Our results generalize the ones given in [3]. [ABSTRACT FROM AUTHOR]

Let R be a prime ring of characteristic not 2, U a nonzero square closed Lie ideal of R and F;G;H be the generalized derivations with associated derivations d,δh of R respectively. In the present paper, we study the situations if one the follwoing holds (1) F(u)G(v)±H(uv)ϵ Z(R), (2) F(u)F (v)±H(vu) ϵ Z(R), for all u,v ϵ U, then U ⊆Z(R). [ABSTRACT FROM AUTHOR]

In this paper, we obtained some fixed point results for continuous mappings satisfying a generalized contractive condition in the setting of two metrics space endowed with a binary relation. Our theorems generalize and extend several known results in the literature. As application, we establish an existence theorem for the solution of a nonlinear first order differential equation. [ABSTRACT FROM AUTHOR]

In this paper, we study Baskakov type positive operators in polynomial weighted spaces of functions of two variables. We obtain some well known operators by using our operators which are special cases of them. We give theorems on approximation, on the degrees of approximations of functions and the Vornovskaya type theorem for these operators. Finally, we present an open problem concerning the q analogue of these operators. [ABSTRACT FROM AUTHOR]

Let λD(λn) be a non-decreasing sequence of positive real numbers tending to1with λn+1 ⩽λn+1;λ1 D1: In the present paper, we introduce the notion of Ʌ-statistical convergence of order, α, Ʌ-statistical Cauchy sequences of order α in random 2-normed spaces and obtain some results. We display examples which show that our method of convergence is more general in random 2-normed space. [ABSTRACT FROM AUTHOR]

Let 0< ρ

In this paper, we prove some Tauberian remainder theorems for Cesàro summability method of noninteger order >α-1. [ABSTRACT FROM AUTHOR]

Let W = {w1;w2; … ;wk} be an ordered set of vertices of G and let v be a vertex of G. The representation r(v|W) of v with respect to W is the k-tuple (d(v,w1),d(v,w2), … ; d(v,wk)). W is called a resolving set or a locating set if every vertex of G is uniquely identified by its distances from the vertices of W, or equivalently, if distinct vertices of G have distinct representations with respect to W . A resolving set of minimum cardinality is called a metric basis for G and this cardinality is the metric dimension of G, denoted by dim(G). Metric dimension is a generalization of affine dimension to arbitrary metric spaces (provided a resolving set exists). In this paper, we study the metric dimension of barycentric subdivision of Cayley graphs Cay(Zn ⊕Zm). We prove that these subdivisions of Cayley graphs have constant metric dimension and only three vertices chosen appropriately suffice to resolve all the vertices of Cayley graphs Cay(Zn⊕Zm). [ABSTRACT FROM AUTHOR]

In this paper, we introduce the multivariate Bernstein-Schurer-Stancu operators. Then, we state the Volkov-type theorem and investigate the order of convergence by means of modulus of continuity and by Lipschitz class functionals. Moreover, the inverse theorems are studied for the multivariate Stancu variant of Bernstein operators. [ABSTRACT FROM AUTHOR]

Zeros of minimizers of p-Ginzburg-Landau functional are helpful to understand the location of vortices of superconductivity and superfluid. When p D 2 and the degree of the boundary data around the boundary is ±1, there exists only one zero of the p-Ginzburg-Landau minimizers in the bounded domain. When p > 2, this becomes a more complicated problem. This paper is concerned with the location of the zeros of a radial minimizer of a p-Ginzburg-Landau type functional. The authors use the method of moving planes and the idea of the proof of Pohozaev's identity to verify that the origin is the unique zero of the radial minimizer in the domain. [ABSTRACT FROM AUTHOR]

In this paper, we introduce ρ-generalized pseudo and ρ-genera-lized quasi with the tool right upper-Dini-derivative and illustrated these by non-trivial examples. Necessary and sufficient optimality conditions are obtained for a nonlinear multiobjective fractional programming problem involving some classes of generalized convexities with the tool-right upper-Dini-derivative. Furthermore, usual duality theorems are proved for a general dual problem using the concept of generalized convex functions. Our results generalize and extend the several results appeared in the literature. [ABSTRACT FROM AUTHOR]

In this paper, a model of two teams of predators interacting with two teams of preys is proposed. The predator teams help each other and so do the prey teams. Therefore, some stability analysis are carried out on the model to detect the stability and instability of the system's equilibrium solutions. Also, the persistence of the solutions is investigated. Finally, the optimal control is applied to the unstable equilibrium solutions. Some numerical simulations are carried out to verify the analytic results. [ABSTRACT FROM AUTHOR]

In this paper we recover convergence and subsequential convergence of a sequence of real numbers regularly generated by another sequence in some sequence spaces under certain conditions. We also give some information about the behavior of a sequence whose generator is given in terms of a moderately divergent sequence. [ABSTRACT FROM AUTHOR]

Let C.(R) denote the center of a ring R and g.(x) be a polynomial of ring C.R(x). An element r ϵ R is called "g(x)-clean" if r = s+u where g(s) = 0 and u is a unit of R and R is g(x)-clean if every element is g(x)-clean. In this paper, we introduce the concept of g(x)-full clean rings and study various properties of them. [ABSTRACT FROM AUTHOR]

A selection of ring theory papers by Jenő Szigeti is reviewed with an emphasis on aspects related to matrix algebras. [ABSTRACT FROM AUTHOR]