Axioms, Volume 11, Issue 3

We show how to apply the well-known fixed-point approach in the study of the existence, uniqueness, and stability of solutions to some particular types of functional equations. Moreover, we also obtain the Ulam stability result for them. The function...

In this study, the limits of the Euler–Bernoulli theory in micromechanics are explored. Raman spectroscopy, which is extremely accurate and reliable, is employed to study the bending of a microbeam of a length of 191 μm. It is found that at...

This article investigates an equation with a rapidly oscillating inhomogeneity and with a rapidly decreasing kernel of an integral operator of Fredholm type. Earlier, differential problems of this type were studied in which the integral term was eith...

The efficiency of transport companies is a very important factor for the companies themselves, as well as for the entire economic system. The main goal of this paper is to develop an integrated model for determining the efficiency of representative t...

In this paper, we were interested in obtaining the exact expression and studying the regions of constant sign of Green’s function related to a second-order perturbed periodic problem coupled with integral boundary conditions at the extremes of the in...

Generalized numbers, arithmetic operators, and derivative operators, grouped in four classes based on symmetry features, are introduced. Their building element is the pair of q-logarithm/q-exponential inverse functions. Some of the objects were previ...

We give a deterministic drawing algorithm to draw a graph onto a torus, which is based on the usual spectral drawing algorithm. For most of the well-known toroidal vertex-transitive graphs, the result drawings give an embedding of the graphs onto the...

We consider a variational–hemivariational inequality in a real Hilbert space, which depends on two parameters. We prove that the inequality is governed by a maximal monotone operator, then we deduce various existence, uniqueness and equivalence resul...

Recently, machine-learning algorithms and existing financial data-analysis methods have been actively studied. Although the term structure of government bonds has been well-researched, the majority of studies only analyze the characteristics of one c...

Portfolio decisions are affected by the volatility of financial markets and investors’ risk tolerance levels. To better allocate portfolios; we introduce risk tolerance into the portfolio management problem by considering the risk contribution...

In this research study, a novel computational algorithm for solving a second-order singular functional differential equation as a generalization of the well-known Lane–Emden and differential-difference equations is presented by using the Bessel...

In this paper, we establish a new integral identity involving differentiable functions, and then we use the newly established identity to prove some Ostrowski–Mercer-type inequalities for differentiable convex functions. It is also demonstrated...

A class of nonassociative algebras is investigated with mild relations induced from metagroup structures. Modules over nonassociative algebras are studied. For a class of modules over nonassociative algebras, their extensions and splitting extensions...

This paper is centered around the creation of new fuzzy connectives using automorphism functions. The fuzzy connectives theory has been implemented in many problems and fields. In particular, the N-negations, t-norms, S-conorms and I-implications con...

In this paper, we propose and study a diffusive HIV infection model with infected cells delay, virus mature delay, abstract function incidence rate and a virus diffusion term. By introducing the reproductive numbers for viral infection $R_0$ and for CTL...

Here, in this article, we introduce and systematically investigate the ideas of deferred weighted statistical Riemann integrability and statistical deferred weighted Riemann summability for sequences of functions. We begin by proving an inclusion the...

We investigate a portfolio selection problem involving an agent’s realistic housing service choice, where the agent not only has to choose the size of house to live in, but also has to select between renting and purchasing a house. Adopting a d...

In this work, we propose a random mixed graph model $G_n(p\left(n\right),q\left(n\right))$ that incorporates both the classical Erdős-Rényi’s random graph model and the random oriented graph model. We show that the empirical spectral distribution of $G_n(p\left(n\right)$...

Since the beginning of the COVID-19 pandemic, vaccination has been the main strategy to contain the spread of the coronavirus. However, with the administration of many types of vaccines and the constant mutation of viruses, the issue of how effective...

Let (X,d) be a metric linear space and a∈X. The point a divides the space into three sets: H_a = {x ∈ X: d(0,x) < d(x,a)}, M_a = {x ∈ X: d(0,x) = d(x,a)} and L_a = {x ∈ X: d(0,x) > d(x,a)}. If the distance is generated by a nor...

The generalized inverse has numerous important applications in aspects of the theoretic research of matrices and statistics. One of the core problems of generalized inverse is finding the necessary and sufficient conditions for the reverse (or the fo...

In this paper, we prove the following: If $n\ge 3$, there is a generic extension of $\mathbf{L}$—the constructible universe—in which it is true that the Separation principle holds for both effective (lightface) classes ${\Sigma }_n^1$ and ${\Pi }_n^1$ of sets of...

The Physics Informed Neural Networks framework is applied to the understanding of the dynamics of COVID-19. To provide the governing system of equations used by the framework, the Susceptible–Infected–Recovered–Death mathematical model is used. This...

The Trojan Y Chromosome Strategy (TYC) is the only genetic biological control method in practice in North America for controlling invasive populations with an XX–XY sex determinism. Herein a modified organism, that is a supermale or feminised s...

Factor analysis is one of the most important statistical tools for analyzing multivariate data (i.e., items) in the social sciences. An essential case is the comparison of multiple groups on a one-dimensional factor variable that can be interpreted a...

This article initiates the study of topological transcendental fields $\mathbb{F}$ which are subfields of the topological field $\mathbb{C}$ of all complex numbers such that $\mathbb{F}$ only consists of rational numbers and a nonempty set of transcendental numbers. $\mathbb{F}$, with the topo...

In this paper, we introduce the notion of fuzzy $\mathcal{R}-\psi -$contractive mappings and prove some relevant results on the existence and uniqueness of fixed points for this type of mappings in the setting of non-Archimedean fuzzy metric spaces....

We consider a mathematical model to describe the interaction between predator and prey that includes predator cannibalism and refuge. We aim to study the dynamics and its long-term behavior of the proposed model, as well as to discuss the effects of...

This paper aims to propose a tool for image classification in medical diagnosis decision support, in a context where computational power is limited and then specific, high-speed computing infrastructures cannot be used (mainly for economic and energy...

A graph is a block graph if its blocks are all cliques. In this paper, we study the average eccentricity of block graphs from the perspective of block order sequences. An equivalence relation is established under the block order sequence and used to...

Unlike most previous studies examining the causal relationship and dependence between exchange rates and real estate prices, this study aims to investigate the causal relationship and dependence between these two variables in a boom-and-bust market s...

Persistent homology is a powerful tool in topological data analysis (TDA) to compute, study, and encode efficiently multi-scale topological features and is being increasingly used in digital image classification. The topological features represent a...

In this paper, a type of high-order compact (HOC) finite difference method is developed for solving two- and three-dimensional unsteady convection diffusion reaction (CDR) equations with variable coefficients. Firstly, an HOC difference scheme is der...

In this paper we initiate the study of boundary value problems for fractional differential equations and inclusions involving $(k,\varphi )$-Hilfer fractional derivative of order in $(1,2]$. In the single-valued case the existence and uniqueness results ar...

Vaccination against the coronavirus disease 2019 (COVID-19) started in early December of 2020 in the USA. The efficacy of the vaccines vary depending on the SARS-CoV-2 variant. Some countries have been able to deploy strong vaccination programs, and...

In this paper, we first introduce the concept of rectangular $G_b$-metric space which generalizes the notion of rectangular metric space and $G_b$-metric space. Then, some fixed point results connected with certain contractions are obtained in the setting...

Precipitation nowcasting is one of the main tasks of weather forecasting that aims to predict rainfall events accurately, even in low-rainfall regions. It has been observed that few studies have been devoted to predicting future radar echo images in...

The Kaczmarz algorithm is an iterative method for solving systems of linear equations. We introduce a randomized Kaczmarz algorithm for solving systems of linear equations in a distributed environment, i.e., the equations within the system are distri...

The ongoing COVID-19 pandemic has caused a paradigm shift in all aspects of contemporary human life. Everyday activities such as shopping have shifted from traditional methods to the ever-more growing online variants, allowing for an increase in elec...

In this work, we investigate the validity of axioms such as Onsager Reciprocal Relations (ORR) for heat transfer in irreversible thermodynamics close to equilibrium. We show that the ORR for this case could be directly derived by introducing the wide...

In this paper, we study the existence and uniqueness of solutions for a coupled implicit system involving $\psi$-Riemann–Liouville fractional derivative with nonlocal conditions. We first transformed the coupled implicit problem into an integral...

Functional data, which provides information about curves, surfaces or anything else varying over a continuum, has become a commonly encountered type of data. The k-nearest neighbor (kNN) method, as a nonparametric method, has become one of the most p...

In recent years, the fractional-order derivative has achieved great success in removing Gaussian noise, impulsive noise, multiplicative noise and so on, but few works have been conducted to remove Cauchy noise. In this paper, we propose a novel nonco...

Let R be a finite ring. In this paper, we mainly explore the conditions to ensure the graph $B{\Gamma }_n$ defined by a system of equations $\left\{f_i\right|i=2,\dots ,n\}$ to be a Cayley graph or a Hamiltonian graph. More precisely, we prove that $B{\Gamma }_n$ is a Cayle...

Let A be an arbitrary matrix in which the number of rows, m, is considerably larger than the number of columns, n. Let the submatrix $A_i,i=1,\dots ,m$, be composed of the first i rows of A. Let ${\beta }_i$ denote the smallest singular value of $A_i$, and le...

In this article we construct parallel solvers analyze the efficiency and accuracy of general parallel solvers for three dimensional parabolic problems with the fractional power of elliptic operators. The proposed discrete method are targeted for gene...

Let $G=(V,E)$ be a connected graph with $\left|V\right|=n$ and $\left|E\right|=m$. A bijection $f:V\left(G\right)\cup E\left(G\right)\to \{1,2,\cdots ,n+m\}$ is called local antimagic total labeling if, for any two adjacent vertices u and v, ${\omega }_t\left(u\right)\ne {\omega }_t\left(v\right)$, where ${\omega }_t\left(u\right)=f\left(u\right)+{\sum }_{e\&is}$...

The existence and uniqueness of a local solution is proved for the incomplete Cauchy type problem to multi-term quasilinear fractional differential equations in Banach spaces with Riemann–Liouville derivatives and bounded operators at them. Non...

Instance reduction is a pre-processing step devised to improve the task of classification. Instance reduction algorithms search for a reduced set of instances to mitigate the low computational efficiency and high storage requirements. Hence, finding...

The purpose of this paper is to provide the first empirical research analysing the effects of the COVID-19 pandemic on the Bulgarian stock market before its onset and in the four pandemic waves. For this purpose, we used a fixed effect panel data reg...