Subjects -> MATHEMATICS (Total: 1118 journals)     - APPLIED MATHEMATICS (92 journals)    - GEOMETRY AND TOPOLOGY (23 journals)    - MATHEMATICS (819 journals)    - MATHEMATICS (GENERAL) (45 journals)    - NUMERICAL ANALYSIS (26 journals)    - PROBABILITIES AND MATH STATISTICS (113 journals) MATHEMATICS (819 journals)                  1 2 3 4 5 | Last

1 2 3 4 5 | Last

Similar Journals
 Afrika MatematikaJournal Prestige (SJR): 0.235 Number of Followers: 3      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1012-9405 - ISSN (Online) 2190-7668 Published by Springer-Verlag  [2658 journals]
• On Ricci–Yamabe soliton and geometrical structure in a perfect fluid
spacetime

Abstract: Abstract In this paper, we studied the geometrical aspects of a perfect fluid spacetime with torse-forming vector field $$\xi$$ under certain curvature restrictions, and Ricci–Yamabe soliton and $$\eta$$ -Ricci–Yamabe soliton in a perfect fluid spacetime. Conditions for the Ricci–Yamabe soliton to be steady, expanding or shrinking are also given. Moreover, when the potential vector field $$\xi$$ of $$\eta$$ -Ricci–Yamabe soliton is of gradient type, we derive a Poisson equation and also looked at its particular cases. Lastly, a non-trivial example of perfect fluid spacetime admitting $$\eta$$ -Ricci–Yamabe soliton is constructed.
PubDate: 2021-09-30

• $${\varphi }$$ φ (Ric)-vector fields on warped product manifolds and
applications

Abstract: Abstract Sufficient and necessary conditions are provided on warped product manifolds and their base and fiber manifolds for a vector field $$\varphi _{j}$$ to be a $$\varphi \left( \mathrm {Ric}\right)$$ -vector field , that is, $$\nabla _{i}\varphi _{j}=\mu R_{ij}$$ where $$R_{ij}$$ is the Ricci tensor of M and $$\mu$$ is a scalar. Two warped product space-times admitting $$\varphi \left( \mathrm {Ric}\right)$$ -vector fields are considered. Lorentzian quasi-Einstein manifolds admitting a time-like $$\varphi \left( \mathrm {Ric} \right)$$ -vector field are shown to be either Ricci simple or a perfect fluid GRW space-time. The generators of a Lorentzian generalized quasi-Einstein manifold admitting a time-like $$\varphi \left( \mathrm {Ric} \right)$$ -vector field are eigenvectors of the Ricci tensor with zero eigenvalue.
PubDate: 2021-09-26

• On Geraghty-Wardowski type contractions and an application

Abstract: Abstract The aim of this work is to extend the Geraghty fixed point result motivated by the approach of Wardowski (Fixed Point Theory Appl 2012:94, 2012). Precisely, we introduce the class of Geraghty $$\alpha$$ - $$\Gamma -\chi$$ -contractions and provide the related fixed point result in (ordered) b-metric spaces. We also derive periodic point results for Geraghty $$\alpha$$ - $$\Gamma -\chi$$ -contractions. Moreover, we provide a concrete example and an application to highlight the realized improvements.
PubDate: 2021-09-14

• Norm form Diophantine equation

Abstract: Abstract In this note, we provide a short proof of the result of Alkabouss et al. (Int J Number Theory 14(4): 1073–1079, 2018), using Runge’s theorem improved by Schinzel.
PubDate: 2021-09-01

• Correction to: Algebraic relations over l-fuzzy soft groups

Abstract: In the online published article, the third author’s “A. Borumand Saeid” affiliation is updated as following “Dept. of Pure Mathematics, Faculty of Mathematics and Computer, Shahid Bahonar University of Kerman, Kerman, Iran”.
PubDate: 2021-09-01

• Controllability of time-varying systems with impulses, delays and nonlocal
conditions

Abstract: Abstract In this paper, we prove the controllability of time-varying semilinear systems with impulses, delay, and nonlocal Conditions, where some ideas are taking from previous works for this kind of systems with impulses and nonlocal conditions only, this is done by using new techniques avoiding fixed point theorems employed by A.E. Bashirov et al. In this case the delay helps us to prove the approximate controllability of this system by pulling back the control solution to a fixed curve in a short time interval, and from this position, we are able to reach a neighborhood of the final state in time $$\tau$$ by assuming that the corresponding linear control system is exactly controllable on any interval $$[t_0, \tau ]$$ , $$0< t_0 < \tau$$ .
PubDate: 2021-09-01

• Fixed point results for Geraghty-weak contractions in ordered partial
rectangular b-metric spaces

Abstract: Abstract In 2017, Parvaneh et al. (J Math Anal 8(1):183–201, 2017) further extended rectangular metric space by introduced partial rectangular b-metric space and utilized the same to prove some fixed point results. Almost at the same time, Roshan et al. (Nonlinear Anal Model Control 21(5):614–634, 2016) generalized Geraghty fixed point results by proving some fixed point results in b-rectangular metric space. In this paper, we prove some ordered-theoretic fixed point results for Geraghty-weak contraction in ordered partial rectangular b-metric space. Our results extend and improve many existing results in literature. We also furnish an example which exhibits the utility of our results.
PubDate: 2021-09-01

• Analysis of a linear and non-linear model for diffusion–dispersion
phenomena of pulp washing by using quintic Hermite interpolation
polynomials

Abstract: Abstract Pulp washing is a prime activity in the process industry that involves diffusion–dispersion phenomena. A huge amount of cost, time, and ecological issues are entailed in waste-water management. To reduce this environmental load and to achieve higher efficiency, the mathematical models are developed and solved with different techniques by the various researchers. In the present study, quintic Hermite interpolating polynomials are used to approximate the trial function for solving the mathematical model of diffusion–dispersion phenomena. The purpose behind this study is to derive an accurate result with less CPU time and effect for some important parameters such as Peclet number, cake thickness, and interstitial velocity of the pulp washing process. Two problems, first with the constant coefficient and second with the variable coefficient are worked out by the proposed scheme. After getting the desired results for the linear model, the method is applied to the nonlinear model. The results indicate that the Peclet number plays a leading role in the pulp washing process whereas, the cake thickness and interstitial velocity both are having a lesser effect. The efficiency, accuracy, and applicability of the method is derived using $$\left\ L \right\ _{2}$$ norm, $$\left\ L \right\ _{\infty }$$ norms, and rate of convergence. The suitability of the proposed technique is well weighed up when compared with the earlier published results and displays a wider scope of industrial applicability.
PubDate: 2021-09-01

• Bounds for the skew Laplacian energy of weighted digraphs

Abstract: Abstract Let $$\mathbb {D}$$ be a simple connected digraph with n vertices and m arcs and let $$W(\mathbb {D})=(\mathbb {D},\omega )$$ be the weighted digraph corresponding to $$\mathbb {D}$$ , where the weights are taken from the set of non-zero real numbers. In this paper, we define the skew Laplacian matrix $$SL(W(\mathbb {D}))$$ and skew Laplacian energy $$SLE(W(\mathbb {D}))$$ of a weighted digraph $$W(\mathbb {D})$$ , which is defined as the sum of the absolute values of the skew Laplacian eigenvalues, that is, $$SLE(W(\mathbb {D}))=\sum _{i=1}^{n} \rho _i$$ , where $$\rho _1,\rho _2, \ldots ,\rho _n$$ are the skew Laplacian eigenvalues of $$W(\mathbb {D})$$ . We show the existence of the real skew Laplacian eigenvalues of a weighted digraph when the weighted digraph has an independent set such that all the vertices in the independent set have the same out-neighbors and in-neighbors. We obtain a Koolen type upper bound for $$SLE(W(\mathbb {D}))$$ . Further, for a connected weighted digraph $$W(\mathbb {D})$$ , we obtain bounds for $$SLE(W(\mathbb {D}))$$ , in terms of different digraph parameters associated with the digraph structure $$\mathbb {D}$$ . We characterize the extremal weighted digraphs attaining these bounds.
PubDate: 2021-09-01

• Fractional Hermite–Hadamard type integral inequalities for functions
whose modulus of the mixed derivatives are co-ordinated $$(log,(\alpha ,m))$$ ( l o g , ( α , m ) ) -preinvex

Abstract: Abstract In this paper, the concept of co-ordinated (log, (s, m))-preinvex functions is introduced. Some new fractional Hermite–Hadamard type inequalities based on new integral identity are established.
PubDate: 2021-09-01

• Neutral slant submersions in paracomplex geometry

Abstract: Abstract In this paper, we investigate some geometric properties of three types of slant submersions whose total space is an almost para-Hermitian manifold.
PubDate: 2021-09-01

• A class of computationally efficient numerical algorithms for locating
multiple zeros

Abstract: Abstract In recent times, many iterative methods for computing multiple zeros of nonlinear functions have been appeared in literature. Different from these existing methods, here we propose a new class of methods with eighth order convergence for multiple zeros. With four evaluations per iteration, the methods satisfy the criterion of attaining optimal convergence of eighth order. Applicability is demonstrated on different examples that illustrates the computational efficiency of novel methods. Comparison of numerical results shows that the proposed techniques possess good convergence compared to existing optimal order techniques. Besides, the accuracy of existing techniques is also challenged which is the main advantage.
PubDate: 2021-09-01

• Second Hankel determinant for universally prestarlike functions related
with exponential function

Abstract: Abstract In Ruscheweyh and Salinas (Math Z 263:607–617, 2009) and Ruscheweyh et al. (Isreal J Math 171:285–304, 2009) the researchers introduced universally convex,universally starlike and universally prestarlike functions in the slit domain $${\mathbb {C}}\backslash [1,\infty {)}.$$ These papers extended the corresponding notions from the unit disc to other discs and half-planes containing the origin. In this paper, we consider universally prestarlike generalized functions of order $$\alpha$$ with $$\alpha \le 1$$ and we obtain upper bounds of the second Hankel determinant $$a_{2}a_{4}-a_{3}^{2}$$ for such functions related with exponential function.
PubDate: 2021-09-01

• Analysis of time delayed Rabies model in human and dog populations with
controls

Abstract: Abstract Rabies is a fatal zoonotic disease caused by a virus through bites or saliva of an infected animal. Dogs are the main reservoir of rabies and responsible for most cases in humans worldwide. In this article, a delay differential equations model for assessing the effects of controls and time delay as incubation period on the transmission dynamics of rabies in human and dog populations is formulated and analyzed. Analysis from the model show that there is a locally and globally asymptotic stable disease-free equilibrium whenever a certain epidemiological threshold, the control reproduction number $$\mathcal {R}_v$$ , is less than unity. Furthermore, the model has a unique endemic equilibrium when $$\mathcal {R}_v$$ exceed unity which is also locally and globally asymptotically stable for all delays. Time delay is found to have influence on the endemicity of rabies. Vaccination of humans and dogs coupled with annual crop of puppies are imposed to curtail the spread of rabies in the populations. Sensitivity analysis on the number of infected humans and dogs revealed that increasing dog vaccination rate and decreasing annual birth of puppies are more effective in human populations. However in dog populations, the vaccination and birth control of puppies, have equal effective measures for rabies control. Numerical experiments are conducted to illustrate the theoretical results and control strategies.
PubDate: 2021-09-01

• On the commutativity degree of a group algebra

Abstract: Abstract The aim of this paper is to give a generalization of the concept of commutativity degree of a finite group G (denoted by d(G)), to the concept of commutativity degree of a group algebra F[G], where G is a finite group and F is a finite field. We prove that two isoclinic groups for which the order of their centers are equal have the same commutativity degree. Finally, we give some lower and upper bounds for the commutativity degree of group algebra F[G] in terms of the order of G, the order of F and d(G).
PubDate: 2021-09-01

• Some properties for certain subclasses of multivalent functions associated
with the $$q-$$ q - difference linear operator

Abstract: Abstract Making use of the $$q-$$ difference operator $$L_{p,q}\left( a,c\right)$$ , we introduce a new two subclasses of $$p-$$ valent analytic functions in the open unit disk. The main objective of the present paper is to investigate the various important properties and characteristics of each of these subclasses. Furthermore, several properties involving neighborhoods and modified Hadamard products of functions in these subclasses are obtained.
PubDate: 2021-09-01

• Perfect unit graphs of commutative Artinian rings

Abstract: Abstract Let R be a commutative ring with identity. The unit graph of R, denoted by G(R), has its set of vertices equal to the set of all elements of R and two distinct vertices x and y are adjacent if and only if $$x+y$$ is a unit of R. In this paper, perfect unit graphs of Artinian rings are investigated.
PubDate: 2021-09-01

• On pseudo-umbilical spacelike submanifolds in indefinite space form
$$\mathcal {M}_p^{n+p}(c)$$ M p n + p ( c )

Abstract: Abstract An intrinsic condition for Pseudo-umbilical spacelike submanifold immersed in indefinite space form is derived, which is used to show that such submanifold is totally geodesic. Next, using a result of Aiyama (Tokyo J Math 18:81–90, 1995), it is proved that Pseudo-umbilical spacelike submanifold is totally umbilical.
PubDate: 2021-09-01

• On generalizations of quasi-prime ideals of an ordered left almost
semigroups

Abstract: Abstract The purposes of this paper are to introduce generalizations of quasi-prime ideals to the context of $$\phi$$ -quasi-prime ideals. Let $$\phi : {\mathcal {I}}(S) \rightarrow {\mathcal {I}}(S) \cup \left\{ \emptyset \right\}$$ be a function where $${\mathcal {I}}(S)$$ is the set of all left ideals of an ordered $${{\mathcal {L}}}{{\mathcal {A}}}$$ -semigroup S. A proper left ideal A of an ordered $${{\mathcal {L}}}{{\mathcal {A}}}$$ -semigroup S is called a $$\phi$$ -quasi-prime ideal, if for each $$a, b\in S$$ with $$ab \in A - \phi (A)$$ , then $$a \in A$$ or $$b\in A$$ . Some characterizations of quasi-prime and $$\phi$$ -quasi-prime ideals are obtained. Moreover, we investigate relationships between weakly quasi-prime, almost quasi-prime, $$\omega$$ -quasi-prime, m-quasi-prime and $$\phi$$ -quasi-prime ideals of ordered $${{\mathcal {L}}}{{\mathcal {A}}}$$ -semigroups. Finally, we obtain necessary and sufficient conditions of $$\phi$$ -quasi-prime ideal in order to be a quasi-prime ideal.
PubDate: 2021-09-01

• A study on a generalization of the n-ary prime hyperideals in a Krasner
(m, n)-hyperring

Abstract: Abstract The aim of this research work is to study a generalization of n-ary prime hyperideals in a Krasner (m, n)-hyperring R called n-ary 2-absorbing hyperideals. We will show some properties of them.
PubDate: 2021-09-01

JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762