Mathematics

8 pages, 242 KiB

Open AccessArticle

The Characterization of Affine Symplectic Curves in ℝ⁴

by Esra Çiçek Çetin and Mehmet Bektaş

Mathematics 2019, 7(1), 110; https://doi.org/10.3390/math7010110 - 21 Jan 2019

Viewed by 3446

Symplectic geometry arises as the natural geometry of phase-space in the equations of classical mechanics. In this study, we obtain new characterizations of regular symplectic curves with respect to the Frenet frame in four-dimensional symplectic space. We also give the characterizations of the [...] Read more.

Symplectic geometry arises as the natural geometry of phase-space in the equations of classical mechanics. In this study, we obtain new characterizations of regular symplectic curves with respect to the Frenet frame in four-dimensional symplectic space. We also give the characterizations of the symplectic circular helices as the third- and fourth-order differential equations involving the symplectic curvatures. Full article

(This article belongs to the Special Issue Differential Geometry)

17 pages, 2001 KiB

Open AccessArticle

The Kumon Method: Its Importance in the Improvement on the Teaching and Learning of Mathematics from the First Levels of Early Childhood and Primary Education

by L. Orcos, R. M. Hernández-Carrera, M. J. Espigares and Á. Alberto Magreñán

Mathematics 2019, 7(1), 109; https://doi.org/10.3390/math7010109 - 21 Jan 2019

Cited by 9 | Viewed by 72477

Abstract

The present work gathers an educational experience based on the application of the personalized Kumon Mathematics Method, carried out in the school year 2015–2016, in which 30,849 students and 230 teachers from several educational centers throughout Spain have participated. We start with a [...] Read more.

The present work gathers an educational experience based on the application of the personalized Kumon Mathematics Method, carried out in the school year 2015–2016, in which 30,849 students and 230 teachers from several educational centers throughout Spain have participated. We start with a theoretical foundation of the Kumon Method and continue with a description of the research methodology used. The empirical analysis carried out has been both in descriptive and correlational terms, using Spearman’s Rho statistic, between the levels at which the students of the sample have started and the Kumon level reached. The results show that the sooner students begin to learn Mathematics with the Kumon Method, the greater the chance of reaching a level of knowledge above their school level, which helps us to demonstrate the potential of this method in the teaching and learning process of Mathematics in the educational levels of Early Childhood and Primary Education. Full article

(This article belongs to the Special Issue New trends in Mathematics Learning)

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16 pages, 322 KiB

Open AccessArticle

Stochastic Game Theoretic Formulation for a Multi-Period DC Pension Plan with State-Dependent Risk Aversion

by Liyuan Wang and Zhiping Chen

Mathematics 2019, 7(1), 108; https://doi.org/10.3390/math7010108 - 21 Jan 2019

Cited by 8 | Viewed by 3115

Abstract

When facing a multi-period defined contribution (DC) pension plan investment problem during the accumulation phase, the risk aversion attitude of a mean-variance investor may depend on state variables. In this paper, we propose a state-dependent risk aversion model which is a linear function [...] Read more.

When facing a multi-period defined contribution (DC) pension plan investment problem during the accumulation phase, the risk aversion attitude of a mean-variance investor may depend on state variables. In this paper, we propose a state-dependent risk aversion model which is a linear function of the current wealth level after contribution. This risk aversion model is reasonable from both the dimensional analysis and the economic point of view. Moreover, we incorporate the wage income factor into our model. In the field of dynamic investment analysis, most studies have irrational situations in their models because of the lack of the positiveness for the wealth process. In view of it, we further improve the work of Wang and Chen by completely eliminating the irrationality of the model. Due to the time-inconsistency of the resulting stochastic control problem, we derive the explicit expressions of the equilibrium control and the corresponding equilibrium value function by adopting the game theoretic framework developed in Björk and Murgoci. Further, two special cases are discussed. Finally, using a more realistic risk aversion coefficient, we provide a series of empirical tests based on the real data from the American market and compare our results with the relevant results in the literature. Full article

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15 pages, 297 KiB

Open AccessArticle

Fixpointed Idempotent Uninorm (Based) Logics

by Eunsuk Yang

Mathematics 2019, 7(1), 107; https://doi.org/10.3390/math7010107 - 20 Jan 2019

Cited by 5 | Viewed by 2837

Abstract

Idempotent uninorms are simply defined by fixpointed negations. These uninorms, called here fixpointed idempotent uninorms, have been extensively studied because of their simplicity, whereas logics characterizing such uninorms have not. Recently, fixpointed uninorm mingle logic (fUML) was introduced, and its standard [...] Read more.

Idempotent uninorms are simply defined by fixpointed negations. These uninorms, called here fixpointed idempotent uninorms, have been extensively studied because of their simplicity, whereas logics characterizing such uninorms have not. Recently, fixpointed uninorm mingle logic (fUML) was introduced, and its standard completeness, i.e., completeness on real unit interval

[0, 1]

, was proved by Baldi and Ciabattoni. However, their proof is not algebraic and does not shed any light on the algebraic feature by which an idempotent uninorm is characterized, using operations defined by a fixpointed negation. To shed a light on this feature, this paper algebraically investigates logics based on fixpointed idempotent uninorms. First, several such logics are introduced as axiomatic extensions of uninorm mingle logic (UML). The algebraic structures corresponding to the systems are then defined, and the results of the associated algebraic completeness are provided. Next, standard completeness is established for the systems using an Esteva–Godo-style approach for proving standard completeness. Full article

(This article belongs to the Special Issue Fuzziness and Mathematical Logic )

6 pages, 746 KiB

Open AccessEditor’s ChoiceArticle

Calculating Nodal Voltages Using the Admittance Matrix Spectrum of an Electrical Network

by Ioannis Dassios, Andrew Keane and Paul Cuffe

Mathematics 2019, 7(1), 106; https://doi.org/10.3390/math7010106 - 20 Jan 2019

Cited by 12 | Viewed by 4535

Abstract

Calculating nodal voltages and branch current flows in a meshed network is fundamental to electrical engineering. This work demonstrates how such calculations can be performed using the eigenvalues and eigenvectors of the Laplacian matrix which describes the connectivity of the electrical network. These [...] Read more.

Calculating nodal voltages and branch current flows in a meshed network is fundamental to electrical engineering. This work demonstrates how such calculations can be performed using the eigenvalues and eigenvectors of the Laplacian matrix which describes the connectivity of the electrical network. These insights should permit the functioning of electrical networks to be understood in the context of spectral analysis. Full article

(This article belongs to the Special Issue Mathematical Methods in Applied Sciences)

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13 pages, 245 KiB

Open AccessArticle

The Four-Parameter PSS Method for Solving the Sylvester Equation

by Hai-Long Shen, Yan-Ran Li and Xin-Hui Shao

Mathematics 2019, 7(1), 105; https://doi.org/10.3390/math7010105 - 20 Jan 2019

Cited by 6 | Viewed by 2840

Abstract

In order to solve the Sylvester equations more efficiently, a new four parameters positive and skew-Hermitian splitting (FPPSS) iterative method is proposed in this paper based on the previous research of the positive and skew-Hermitian splitting (PSS) iterative method. We prove that when [...] Read more.

In order to solve the Sylvester equations more efficiently, a new four parameters positive and skew-Hermitian splitting (FPPSS) iterative method is proposed in this paper based on the previous research of the positive and skew-Hermitian splitting (PSS) iterative method. We prove that when coefficient matrix

A

and

B

satisfy certain conditions, the FPPSS iterative method is convergent in the parameter’s value region. The numerical experiment results show that compared with previous iterative method, the FPPSS iterative method is more effective in terms of iteration number IT and runtime. Full article

6 pages, 214 KiB

Open AccessArticle

Completness of Statistical Structures

by Barbara Opozda

Mathematics 2019, 7(1), 104; https://doi.org/10.3390/math7010104 - 19 Jan 2019

Viewed by 2902

Abstract

In this survey note, we discuss the notion of completeness for statistical structures. There are at least three connections whose completeness might be taken into account, namely, the Levi-Civita connection of the given metric, the statistical connection, and its conjugate. Especially little is [...] Read more.

In this survey note, we discuss the notion of completeness for statistical structures. There are at least three connections whose completeness might be taken into account, namely, the Levi-Civita connection of the given metric, the statistical connection, and its conjugate. Especially little is known on the completeness of statistical connections. Full article

(This article belongs to the Special Issue Differential Geometry)

13 pages, 268 KiB

Open AccessArticle

Improved Convergence Analysis of Gauss-Newton-Secant Method for Solving Nonlinear Least Squares Problems

by Ioannis Argyros, Stepan Shakhno and Yurii Shunkin

Mathematics 2019, 7(1), 99; https://doi.org/10.3390/math7010099 - 18 Jan 2019

Cited by 6 | Viewed by 3275

Abstract

We study an iterative differential-difference method for solving nonlinear least squares problems, which uses, instead of the Jacobian, the sum of derivative of differentiable parts of operator and divided difference of nondifferentiable parts. Moreover, we introduce a method that uses the derivative of [...] Read more.

We study an iterative differential-difference method for solving nonlinear least squares problems, which uses, instead of the Jacobian, the sum of derivative of differentiable parts of operator and divided difference of nondifferentiable parts. Moreover, we introduce a method that uses the derivative of differentiable parts instead of the Jacobian. Results that establish the conditions of convergence, radius and the convergence order of the proposed methods in earlier work are presented. The numerical examples illustrate the theoretical results. Full article

(This article belongs to the Special Issue Computational Methods in Analysis and Applications)

19 pages, 1223 KiB

Open AccessArticle

Application of Optimization to Select Contractors to Develop Strategies and Policies for the Development of Transport Infrastructure

by Chia-Nan Wang, Tien-Muoi Le and Han-Khanh Nguyen

Mathematics 2019, 7(1), 98; https://doi.org/10.3390/math7010098 - 18 Jan 2019

Cited by 5 | Viewed by 3518

Abstract

Many factors influence the efficiency and quality of transport works. In particular, consultants and construction contractors of these works play important roles, and critical factors directly affect the quality of traffic works. If the quality of consultancy and construction is good, the project [...] Read more.

Many factors influence the efficiency and quality of transport works. In particular, consultants and construction contractors of these works play important roles, and critical factors directly affect the quality of traffic works. If the quality of consultancy and construction is good, the project will reduce the total investment; if the contractor is good, the completion time of the new project is guaranteed, thus reducing construction costs. The longer the construction time is, the higher the cost of the project. In this study, the authors used optimal algorithms to evaluate past, present, and future contractors’ technical, technological, and performance effectiveness. Research results show that bidders are divided into three groups: highly effective bidders, stable contractors, and inefficient groups. Research results for this subject will help the government, regulatory agencies, and investors select good contractors as the basis for developing strategies and policies for the development of transport infrastructure. Full article

(This article belongs to the Special Issue Application of Optimization in Production, Logistics, Inventory, Supply Chain Management and Block Chain)

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14 pages, 496 KiB

Open AccessArticle

A Novel Interval Three-Way Concept Lattice Model with Its Application in Medical Diagnosis

by Junhua Hu, Dan Chen and Pei Liang

Mathematics 2019, 7(1), 103; https://doi.org/10.3390/math7010103 - 18 Jan 2019

Cited by 21 | Viewed by 2952

Abstract

Medical diagnosis has been recognized as one of the key processes in clinical medicine, which determines diseases from some given symptoms. Nonetheless, previous works about medical diagnosis have some drawbacks because medical data are usually fuzzy, uncertain, incomplete and imprecise. To achieve the [...] Read more.

Medical diagnosis has been recognized as one of the key processes in clinical medicine, which determines diseases from some given symptoms. Nonetheless, previous works about medical diagnosis have some drawbacks because medical data are usually fuzzy, uncertain, incomplete and imprecise. To achieve the optimal medical diagnosis decision by reducing cost and enhancing accuracy, this paper develops a new method named interval three-way concept lattice model. Firstly, we redefine the decision rules and metric function of three-way decision based on interval concept lattice. Secondly, we build a visualized hierarchical structure of relationship between concepts through interval concept construction algorithm which helps us to make decision preferably and clearly. Finally, we establish a dynamic strategy optimization model for medical diagnosis decision making. In addition, a medical case demonstrates the effectiveness and feasibility of this proposed model. Full article

(This article belongs to the Section Mathematics and Computer Science)

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10 pages, 268 KiB

Open AccessArticle

Fisher-Type Fixed Point Results in b-Metric Spaces

by Badr Alqahtani, Andreea Fulga, Erdal Karapınar and Ali Özturk

Mathematics 2019, 7(1), 102; https://doi.org/10.3390/math7010102 - 18 Jan 2019

Cited by 5 | Viewed by 3976

Abstract

In this paper, we prove some common fixed-point theorems for two self-mappings in the context of a complete b-metric space by proposing a new contractive type condition. Further, we derive a result for three self-mappings in the same setting. We provide two [...] Read more.

In this paper, we prove some common fixed-point theorems for two self-mappings in the context of a complete b-metric space by proposing a new contractive type condition. Further, we derive a result for three self-mappings in the same setting. We provide two examples to demonstrate the validity of the obtained results. Full article

(This article belongs to the Special Issue Recent Advances in Fixed Point Theory and Its Applications)

23 pages, 1082 KiB

Open AccessArticle

Stability Analysis of Quaternion-Valued Neutral-Type Neural Networks with Time-Varying Delay

by Jinlong Shu, Lianglin Xiong, Tao Wu and Zixin Liu

Mathematics 2019, 7(1), 101; https://doi.org/10.3390/math7010101 - 18 Jan 2019

Cited by 14 | Viewed by 2910

Abstract

This paper addresses the problem of global

μ

-stability for quaternion-valued neutral-type neural networks (QVNTNNs) with time-varying delays. First, QVNTNNs are transformed into two complex-valued systems by using a transformation to reduce the complexity of the computation generated by the non-commutativity of quaternion [...] Read more.

This paper addresses the problem of global

μ

-stability for quaternion-valued neutral-type neural networks (QVNTNNs) with time-varying delays. First, QVNTNNs are transformed into two complex-valued systems by using a transformation to reduce the complexity of the computation generated by the non-commutativity of quaternion multiplication. A new convex inequality in a complex field is introduced. In what follows, the condition for the existence and uniqueness of the equilibrium point is primarily obtained by the homeomorphism theory. Next, the global stability conditions of the complex-valued systems are provided by constructing a novel Lyapunov–Krasovskii functional, using an integral inequality technique, and reciprocal convex combination approach. The gained global

μ

-stability conditions can be divided into three different kinds of stability forms by varying the positive continuous function

μ (t)

. Finally, three reliable examples and a simulation are given to display the effectiveness of the proposed methods. Full article

(This article belongs to the Section Mathematics and Computer Science)

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10 pages, 275 KiB

Open AccessArticle

Fractional Metric Dimension of Generalized Jahangir Graph

by Jia-Bao Liu, Agha Kashif, Tabasam Rashid and Muhammad Javaid

Mathematics 2019, 7(1), 100; https://doi.org/10.3390/math7010100 - 18 Jan 2019

Cited by 59 | Viewed by 3763

Abstract

Arumugam and Mathew [Discret. Math. 2012, 312, 1584–1590] introduced the notion of fractional metric dimension of a connected graph. In this paper, a combinatorial technique is devised to compute it. In addition, using this technique the fractional metric dimension of [...] Read more.

Arumugam and Mathew [Discret. Math. 2012, 312, 1584–1590] introduced the notion of fractional metric dimension of a connected graph. In this paper, a combinatorial technique is devised to compute it. In addition, using this technique the fractional metric dimension of the generalized Jahangir graph

J_{m, k}

is computed for

k \geq 0

and

m = 5

. Full article

(This article belongs to the Special Issue Discrete Optimization: Theory, Algorithms, and Applications)

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16 pages, 582 KiB

Open AccessArticle

Multi-Criteria Decision-Making Method Using Heronian Mean Operators under a Bipolar Neutrosophic Environment

by Changxing Fan, Jun Ye, Sheng Feng, En Fan and Keli Hu

Mathematics 2019, 7(1), 97; https://doi.org/10.3390/math7010097 - 17 Jan 2019

Cited by 19 | Viewed by 3471

Abstract

In real applications, most decisions are fuzzy decisions, and the decision results mainly depend on the choice of aggregation operators. In order to aggregate information more scientifically and reasonably, the Heronian mean operator was studied in this paper. Considering the advantages and limitations [...] Read more.

In real applications, most decisions are fuzzy decisions, and the decision results mainly depend on the choice of aggregation operators. In order to aggregate information more scientifically and reasonably, the Heronian mean operator was studied in this paper. Considering the advantages and limitations of the Heronian mean (HM) operator, four Heronian mean operators for bipolar neutrosophic number (BNN) are proposed: the BNN generalized weighted HM (BNNGWHM) operator, the BNN improved generalized weighted HM (BNNIGWHM) operator, the BNN generalized weighted geometry HM (BNNGWGHM) operator, and the BNN improved generalized weighted geometry HM (BNNIGWGHM) operator. Then, their propositions were examined. Furthermore, two multi-criteria decision methods based on the proposed BNNIGWHM and BNNIGWGHM operator are introduced under a BNN environment. Lastly, the effectiveness of the new methods was verified with an example. Full article

(This article belongs to the Special Issue New Challenges in Neutrosophic Theory and Applications)

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10 pages, 1531 KiB

Open AccessArticle

Two Classes of Entropy Measures for Complex Fuzzy Sets

by Lvqing Bi, Zhiqiang Zeng, Bo Hu and Songsong Dai

Mathematics 2019, 7(1), 96; https://doi.org/10.3390/math7010096 - 17 Jan 2019

Cited by 41 | Viewed by 2951

Abstract

Complex fuzzy sets are characterized by complex-valued membership functions, whose range is extended from the traditional fuzzy range of [0,1] to the unit circle in the complex plane. In this paper, we define two kinds of entropy measures for complex fuzzy sets, called [...] Read more.

Complex fuzzy sets are characterized by complex-valued membership functions, whose range is extended from the traditional fuzzy range of [0,1] to the unit circle in the complex plane. In this paper, we define two kinds of entropy measures for complex fuzzy sets, called type-A and type-B entropy measures, and analyze their rotational invariance properties. Among them, two formulas of type-A entropy measures possess the attribute of rotational invariance, whereas the other two formulas of type-B entropy measures lack this characteristic. Full article

(This article belongs to the Special Issue Fuzziness and Mathematical Logic )

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17 pages, 280 KiB

Open AccessArticle

Neutrosophic Multigroups and Applications

by Vakkas Uluçay and Memet Şahin

Mathematics 2019, 7(1), 95; https://doi.org/10.3390/math7010095 - 17 Jan 2019

Cited by 19 | Viewed by 3315

Abstract

In recent years, fuzzy multisets and neutrosophic sets have become a subject of great interest for researchers and have been widely applied to algebraic structures include groups, rings, fields and lattices. Neutrosophic multiset is a generalization of multisets and neutrosophic sets. In this [...] Read more.

In recent years, fuzzy multisets and neutrosophic sets have become a subject of great interest for researchers and have been widely applied to algebraic structures include groups, rings, fields and lattices. Neutrosophic multiset is a generalization of multisets and neutrosophic sets. In this paper, we proposed a algebraic structure on neutrosophic multisets is called neutrosophic multigroups which allow the truth-membership, indeterminacy-membership and falsity-membership sequence have a set of real values between zero and one. This new notation of group as a bridge among neutrosophic multiset theory, set theory and group theory and also shows the effect of neutrosophic multisets on a group structure. We finally derive the basic properties of neutrosophic multigroups and give its applications to group theory. Full article

(This article belongs to the Special Issue New Challenges in Neutrosophic Theory and Applications)

8 pages, 2869 KiB

Open AccessArticle

A New Family of Chaotic Systems with Different Closed Curve Equilibrium

by Xinhe Zhu and Wei-Shih Du

Mathematics 2019, 7(1), 94; https://doi.org/10.3390/math7010094 - 17 Jan 2019

Cited by 14 | Viewed by 3385

Abstract

Chaotic systems with hidden attractors, infinite number of equilibrium points and different closed curve equilibrium have received much attention in the past six years. In this work, we introduce a new family of chaotic systems with different closed curve equilibrium. Using the methods [...] Read more.

Chaotic systems with hidden attractors, infinite number of equilibrium points and different closed curve equilibrium have received much attention in the past six years. In this work, we introduce a new family of chaotic systems with different closed curve equilibrium. Using the methods of equilibrium points, phase portraits, maximal Lyapunov exponents, Kaplan–Yorke dimension, and eigenvalues, we analyze the dynamical properties of the proposed systems and extend the general knowledge of such systems. Full article

(This article belongs to the Special Issue Fixed Point Theory and Dynamical Systems with Applications)

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22 pages, 1402 KiB

Open AccessArticle

Numerical Gradient Schemes for Heat Equations Based on the Collocation Polynomial and Hermite Interpolation

by Hou-Biao Li, Ming-Yan Song, Er-Jie Zhong and Xian-Ming Gu

Mathematics 2019, 7(1), 93; https://doi.org/10.3390/math7010093 - 17 Jan 2019

Cited by 4 | Viewed by 2886

Abstract

As is well-known, the advantage of the high-order compact difference scheme (H-OCD) is that it is unconditionally stable and convergent on the order

O (τ^{2} + h^{4})

(where

τ

is the time step size and h is the mesh [...] Read more.

As is well-known, the advantage of the high-order compact difference scheme (H-OCD) is that it is unconditionally stable and convergent on the order

O (τ^{2} + h^{4})

(where

τ

is the time step size and h is the mesh size), under the maximum norm for a class of nonlinear delay partial differential equations with initial and Dirichlet boundary conditions. In this article, a new numerical gradient scheme based on the collocation polynomial and Hermite interpolation is presented. The convergence order of this kind of method is also

O (τ^{2} + h^{4})

under the discrete maximum norm when the spatial step size is twice the one of H-OCD, which accelerates the computational process. In addition, some corresponding analyses are made and the Richardson extrapolation technique is also considered in the time direction. The results of numerical experiments are consistent with the theoretical analysis. Full article

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13 pages, 246 KiB

Open AccessArticle

Resistance Distance in the Double Corona Based on R-Graph

by Li Zhang, Jing Zhao, Jia-Bao Liu and Salama Nagy Daoud

Mathematics 2019, 7(1), 92; https://doi.org/10.3390/math7010092 - 17 Jan 2019

Cited by 4 | Viewed by 3521

Abstract

Let

G_{0}

be a connected graph on n vertices and m edges. The R-graph

R (G_{0})

of

G_{0}

is a graph obtained from

G_{0}

by adding a new vertex corresponding to each edge of [...] Read more.

Let

G_{0}

be a connected graph on n vertices and m edges. The R-graph

R (G_{0})

of

G_{0}

is a graph obtained from

G_{0}

by adding a new vertex corresponding to each edge of

G_{0}

and by joining each new vertex to the end points of the edge corresponding to it. Let

G_{1}

and

G_{2}

be graphs on

n_{1}

and

n_{2}

vertices, respectively. The R-graph double corona

G_{0}^{(R)} \circ {G_{1}, G_{2}}

of

G_{0}

,

G_{1}

and

G_{2}

, is the graph obtained by taking one copy of

R (G_{0})

, n copies of

G_{1}

and m copies of

G_{2}

and then by joining the i-th old-vertex of

R (G_{0})

to every vertex of the i-th copy of

G_{1}

and the j-th new vertex of

R (G_{0})

to every vertex of the j-th copy of

G_{2}

. In this paper, we consider resistance distance in

G_{0}^{(R)} \circ {G_{1}, G_{2}}

. Moreover, we give an example to illustrate the correction and efficiency of the proposed method. Full article

(This article belongs to the Special Issue Computational Methods in Analysis and Applications)

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33 pages, 806 KiB

Open AccessArticle

q-Rung Orthopair Fuzzy Competition Graphs with Application in the Soil Ecosystem

by Amna Habib, Muhammad Akram and Adeel Farooq

Mathematics 2019, 7(1), 91; https://doi.org/10.3390/math7010091 - 16 Jan 2019

Cited by 55 | Viewed by 5095

Abstract

The q-rung orthopair fuzzy set is a powerful tool for depicting fuzziness and uncertainty, as compared to the Pythagorean fuzzy model. The aim of this paper is to present q-rung orthopair fuzzy competition graphs (q-ROFCGs) and their generalizations, including [...] Read more.

The q-rung orthopair fuzzy set is a powerful tool for depicting fuzziness and uncertainty, as compared to the Pythagorean fuzzy model. The aim of this paper is to present q-rung orthopair fuzzy competition graphs (q-ROFCGs) and their generalizations, including q-rung orthopair fuzzy k-competition graphs, p-competition q-rung orthopair fuzzy graphs and m-step q-rung orthopair fuzzy competition graphs with several important properties. The study proposes the novel concepts of q-rung orthopair fuzzy cliques and triangulated q-rung orthopair fuzzy graphs with real-life characterizations. In particular, the present work evolves the notion of competition number and m-step competition number of q-rung picture fuzzy graphs with algorithms and explores their bounds in connection with the size of the smallest q-rung orthopair fuzzy edge clique cover. In addition, an application is illustrated in the soil ecosystem with an algorithm to highlight the contributions of this research article in practical applications. Full article

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21 pages, 1336 KiB

Open AccessArticle

An Efficient Spectral Method to Solve Multi-Dimensional Linear Partial Different Equations Using Chebyshev Polynomials

by Sahuck Oh

Mathematics 2019, 7(1), 90; https://doi.org/10.3390/math7010090 - 16 Jan 2019

Cited by 8 | Viewed by 3983

Abstract

We present a new method to efficiently solve a multi-dimensional linear Partial Differential Equation (PDE) called the quasi-inverse matrix diagonalization method. In the proposed method, the Chebyshev-Galerkin method is used to solve multi-dimensional PDEs spectrally. Efficient calculations are conducted by converting dense equations [...] Read more.

We present a new method to efficiently solve a multi-dimensional linear Partial Differential Equation (PDE) called the quasi-inverse matrix diagonalization method. In the proposed method, the Chebyshev-Galerkin method is used to solve multi-dimensional PDEs spectrally. Efficient calculations are conducted by converting dense equations of systems sparse using the quasi-inverse technique and by separating coupled spectral modes using the matrix diagonalization method. When we applied the proposed method to 2-D and 3-D Poisson equations and coupled Helmholtz equations in 2-D and a Stokes problem in 3-D, the proposed method showed higher efficiency in all cases than other current methods such as the quasi-inverse method and the matrix diagonalization method in solving the multi-dimensional PDEs. Due to this efficiency of the proposed method, we believe it can be applied in various fields where multi-dimensional PDEs must be solved. Full article

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14 pages, 286 KiB

Open AccessArticle

Ball Comparison for Some Efficient Fourth Order Iterative Methods Under Weak Conditions

by Ioannis K. Argyros and Ramandeep Behl

Mathematics 2019, 7(1), 89; https://doi.org/10.3390/math7010089 - 16 Jan 2019

Viewed by 2796

Abstract

We provide a ball comparison between some 4-order methods to solve nonlinear equations involving Banach space valued operators. We only use hypotheses on the first derivative, as compared to the earlier works where they considered conditions reaching up to 5-order derivative, although these [...] Read more.

We provide a ball comparison between some 4-order methods to solve nonlinear equations involving Banach space valued operators. We only use hypotheses on the first derivative, as compared to the earlier works where they considered conditions reaching up to 5-order derivative, although these derivatives do not appear in the methods. Hence, we expand the applicability of them. Numerical experiments are used to compare the radii of convergence of these methods. Full article

(This article belongs to the Special Issue Iterative Methods for Solving Nonlinear Equations and Systems)

11 pages, 273 KiB

Open AccessArticle

Coefficient Inequalities of Functions Associated with Hyperbolic Domains

by Sarfraz Nawaz Malik, Shahid Mahmood, Mohsan Raza, Sumbal Farman, Saira Zainab and Nazeer Muhammad

Mathematics 2019, 7(1), 88; https://doi.org/10.3390/math7010088 - 16 Jan 2019

Cited by 4 | Viewed by 2609

Abstract

In this work, our focus is to study the Fekete-Szegö functional in a different and innovative manner, and to do this we find its upper bound for certain analytic functions which give hyperbolic regions as image domain. The upper bounds obtained in this [...] Read more.

In this work, our focus is to study the Fekete-Szegö functional in a different and innovative manner, and to do this we find its upper bound for certain analytic functions which give hyperbolic regions as image domain. The upper bounds obtained in this paper give refinement of already known results. Moreover, we extend our work by calculating similar problems for the inverse functions of these certain analytic functions for the sake of completeness. Full article

(This article belongs to the Special Issue Inequalities)

12 pages, 274 KiB

Open AccessArticle

On the Zeros of the Differential Polynomial φ(z)f²(z)f′(z)² − 1

by Junfeng Xu and Shuichao Ye

Mathematics 2019, 7(1), 87; https://doi.org/10.3390/math7010087 - 16 Jan 2019

Cited by 4 | Viewed by 2374

Abstract

In this study, the value distribution of the differential polynomial

φ f^{2} f^{' 2} - 1

is considered, where f is a transcendental meromorphic function,

φ (≢ 0)

is a small function of f by the reduced counting function. [...] Read more.

In this study, the value distribution of the differential polynomial

φ f^{2} f^{' 2} - 1

is considered, where f is a transcendental meromorphic function,

φ (≢ 0)

is a small function of f by the reduced counting function. This result improves the existed theorems which obtained by Jiang (Bull Korean Math Soc 53: 365-371, 2016) and also give a quantitative inequality of

φ f f^{'} - 1

. Full article

(This article belongs to the Section Mathematics and Computer Science)

15 pages, 10797 KiB

Open AccessArticle

Secondary, Near Chaotic Patterns from Analogue Drawing Machines

by Jack Tait

Mathematics 2019, 7(1), 86; https://doi.org/10.3390/math7010086 - 15 Jan 2019

Cited by 2 | Viewed by 8350

Abstract

Chaos is now recognized as one of three emergent topics of study in the 21c. It is seen as appropriate to examine this in art practice. Accordingly, this paper is written from an art perspective. It does not mimic a traditional mathematical or [...] Read more.

Chaos is now recognized as one of three emergent topics of study in the 21c. It is seen as appropriate to examine this in art practice. Accordingly, this paper is written from an art perspective. It does not mimic a traditional mathematical or science format, presenting hypothesis, repeat testing, and a conclusion. The art process operates differently, and chaos is seen in graphic terms, veers more to philosophy, and is obviously subjective. The intent in researching secondary patterns, near the edge of chaos, is to make expressive graphic art images as art works, testing how close they might come to a chaotic state whilst retaining visual coherence. This underpins the author’s current research, but it is recognised as being a very narrow and specialized subset of analogue art activity. The way in which analogue generative art differs from the more common use of digital computers is addressed. Unlike the latter, the work involves designing and making the machines, making the programmers, and writing the algorithms; this is implicit in the text. A brief look at drawing machine history is presented, demonstrating how the author’s machines differ from others. A contextual cross refence is also made, where appropriate, to artists using digital means. The author’s research has documented practitioners who choose an analogue route to make art. However, hardly any of them create programmes to generate coherent images. This shortage creates problems when attempting to cite similar work. Whilst the general principle underlying the work presented is algorithmic, a significant element of quasi-random input is incorporated, consistent with a study of chaos. Emergent facets are implicit, such as the art process, design problem solving, the relationship between quasi-random and determinism, the psychology of evaluation, and the philosophy of how art works. From the author’s Programmable Analogue Drawing Machines, two are selected for this paper which draw Lissajous figures, use X:Y axes, turntables, Direct Current motors, and an asynchronous pen-lift mechanism. Simple instructions generate complex patterns in a similar vein to Alan Turings topics of phyllotaxis and morphogenesis. These aspects will be discussed, presenting two machines that demonstrate these properties. Full article

(This article belongs to the Special Issue Topological Modeling)

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15 pages, 271 KiB

Open AccessArticle

Alexandrov L-Fuzzy Pre-Proximities

by Yong Chan Kim and Ju-Mok Oh

Mathematics 2019, 7(1), 85; https://doi.org/10.3390/math7010085 - 15 Jan 2019

Cited by 1 | Viewed by 2260

Abstract

In this paper, we introduce the concepts of Alexandrov L-fuzzy pre-proximities on complete residuated lattices. Moreover, we investigate their relations among Alexandrov L-fuzzy pre-proximities, Alexandrov L-fuzzy topologies, L-fuzzy upper approximate operators, and L-fuzzy lower approximate operators. We give their examples. Full article

(This article belongs to the Section Mathematics and Computer Science)

7 pages, 231 KiB

Open AccessArticle

Interpolative Ćirić-Reich-Rus Type Contractions via the Branciari Distance

by Hassen Aydi, Chi-Ming Chen and Erdal Karapınar

Mathematics 2019, 7(1), 84; https://doi.org/10.3390/math7010084 - 15 Jan 2019

Cited by 105 | Viewed by 3554

Abstract

In this paper, we initiate the concept of interpolative Ćirić-Reich-Rus type contractions via the Branciari distance and prove some related fixed points results for such mappings. Moreover, an example is provided to show the useability of our obtained results. Full article

(This article belongs to the Special Issue Recent Advances in Fixed Point and Best Proximity Point Problems and Their Applications)

12 pages, 399 KiB

Open AccessArticle

The Extremal Cacti on Multiplicative Degree-Kirchhoff Index

by Fangguo He and Zhongxun Zhu

Mathematics 2019, 7(1), 83; https://doi.org/10.3390/math7010083 - 15 Jan 2019

Cited by 2 | Viewed by 2538

Abstract

For a graph G, the resistance distance

r_{G} (x, y)

is defined to be the effective resistance between vertices x and y, the multiplicative degree-Kirchhoff index [...] Read more.

For a graph G, the resistance distance

r_{G} (x, y)

is defined to be the effective resistance between vertices x and y, the multiplicative degree-Kirchhoff index

R^{*} (G) = \sum_{{x, y} \subset V (G)} d_{G} (x) d_{G} (y) r_{G} (x, y)

, where

d_{G} (x)

is the degree of vertex x, and

V (G)

denotes the vertex set of G. L. Feng et al. obtained the element in

C a c t (n; t)

with first-minimum multiplicative degree-Kirchhoff index. In this paper, we first give some transformations on

R^{*} (G)

, and then, by these transformations, the second-minimum multiplicative degree-Kirchhoff index and the corresponding extremal graph are determined, respectively. Full article

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16 pages, 331 KiB

Open AccessArticle

The Structure of Moduloid on a Nexus

by Masoud Bolourian, Reza Kamrani and Abbas Hasankhani

Mathematics 2019, 7(1), 82; https://doi.org/10.3390/math7010082 - 14 Jan 2019

Cited by 2 | Viewed by 3813

Abstract

In this paper, the notion of moduloid on a nexus is introduced. Moreover, the concept of submoduloid is defined and some different submoduloids are introdused. Also, several interesting facts about submoduloids are proved. Finally, a homomorphism between two moduloids is defined and some [...] Read more.

In this paper, the notion of moduloid on a nexus is introduced. Moreover, the concept of submoduloid is defined and some different submoduloids are introdused. Also, several interesting facts about submoduloids are proved. Finally, a homomorphism between two moduloids is defined and some related results are investigated. Full article

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17 pages, 477 KiB

Open AccessArticle

Exact Solution for the Heat Transfer of Two Immiscible PTT Fluids Flowing in Concentric Layers through a Pipe

by Abdul Majeed Siddiqui, Muhammad Zeb, Tahira Haroon and Qurat-ul-Ain Azim

Mathematics 2019, 7(1), 81; https://doi.org/10.3390/math7010081 - 14 Jan 2019

Cited by 11 | Viewed by 3419

Abstract

This article investigates the heat transfer flow of two layers of Phan-Thien-Tanner (PTT) fluids though a cylindrical pipe. The flow is assumed to be steady, incompressible, and stable and the fluid layers do not mix with each other. The fluid flow and heat [...] Read more.

This article investigates the heat transfer flow of two layers of Phan-Thien-Tanner (PTT) fluids though a cylindrical pipe. The flow is assumed to be steady, incompressible, and stable and the fluid layers do not mix with each other. The fluid flow and heat transfer equations are modeled using the linear PTT fluid model. Exact solutions for the velocity, flow rates, temperature profiles, and stress distributions are obtained. It has also been shown that one can recover the Newtonian fluid results from the obtained results by putting the non-Newtonian parameters to zero. These results match with the corresponding results for Newtonian fluids already present in the literature. Graphical analysis of the behavior of the fluid velocities, temperatures, and stresses is also presented at the end. It is also shown that maximum velocity occurs in the inner fluid layer. Full article

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Mathematics, Volume 7, Issue 1 (January 2019) – 110 articles

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