Afrika Matematika最新文献

This paper addresses the problem of estimating the finite population mean (overline{Y}) of the study variable (y) using two auxiliary variables in systematic sampling. We have suggested a difference-type estimator and its improved version, and then their properties have been studied. It has been shown that the proposed class of estimators is more efficient than the recently proposed estimators due to Tailor et al. (Stat Transit 14: 391–398, 2013) and Khan and Singh (J Prob Stat https://doi.org/10.1155/2015/248374, 2015). An empirical study has been undertaken to evaluate the performance of the suggested estimator over other existing estimators.

In this paper, we proposed a modified Tseng’s splitting iterative algorithm for approximating a solution of split feasibility problem for zero and fixed point problems. By incorporating an inertial extrapolation method and Halpern iterative technique, we established a strong convergence result for approximating a solution of split fixed point problem for a nonexpansive and quasinonexpansive mapping which is also a zero point of sum of two monotone operators in the framework of real Hilbert spaces. Furthermore, we present a numerical example to support our main result. The results obtained in this paper improve, extend and unify some related results in the literature.

This paper considers some optimal classes of difference and ratio type estimators for the estimation of population mean using higher order moments viz variance of auxiliary variable with the aim of improvement over its entrants existing till date. The bias and mean square error of the considered estimators are derived using Taylor series method up to the first order of approximation. The theoretical results have been determined and appraised with a computational study using real and artificially generated data sets. The computational results are turned out to be rather advance providing better improvement over the contemporary estimators.

In this paper, we discover Anjaneyulu’s pseudo-symmetricity with the help of interval-valued fuzzy membership function. In semigroups, we propose the concept of (i–v) pseudo-symmetric (semipseudo-symmetric, semiprimary) fuzzy ideals and cultivate their different properties. Moreover, we mention some relationships among three (i–v) fuzzy radicals. Lastly, we verify that the (i–v) fuzzy ideals, namely, (i–v) completely prime, (i–v) completely semiprime, (i–v) pseudo-symmetric and (i–v) primary fuzzy ideals are equivalent in some specific semigroups.

In the present paper we characterize 3-dimensional generalized Sasakian-space-forms admitting some solitons such as Einstein solitons, (eta )-Einstein solitons,(eta )-Ricci solitons, gradient (eta )-Ricci solitons and (eta )-Yamabe solitons. First we show that an Einstein soliton on a 3-dimensional generalized Sasakian-space-form (M(f_1,f_2,f_3)) becomes a Ricci soliton and the soliton is shrinking, steady and expanding according as ((f_1 - f_3) < 0, = 0) and (> 0), respectively, where (f_1), (f_2) and (f_3) are smooth functions. Also, we establish that if a 3-dimensional generalized Sasakian-space-form (M(f_1,f_2,f_3)) admits a gradient (eta )-Ricci soliton with potential function f, then (f = log(frac{f_1-f_3}{k})^2,) where k is a constant. Next, we prove that if a 3-dimensional generalized Sasakian-space-form (M(f_1,f_2,f_3)) is an (eta )-Yamabe soliton, then the soliton reduces to a Yamabe soliton and the scalar curvature is constant. Finally, we construct an example which proves the existence of our results.

This article considers a life test scheme called the adaptive type-II progressive hybrid censoring scheme introduced by Ng et al. (Naval Res Logist 5(8):687–698, 2009). Based on this type of censoring, we draw inferences about the three well-known measures of overlap, namely Matusita’s measure (( rho )), Morisita’s measure ((lambda )), and Weitzman’s ((Delta )) for two exponential populations with different means. The asymptotic bias and variance of the overlap measure estimators are derived. Monte Carlo evaluations are employed in cases with small sample sizes, where computing the precision or bias of these estimators becomes challenging due to the lack of closed-form expressions for their variances and exact sampling distributions. Confidence intervals for those measures are also constructed via the bootstrap method and Taylor expansion approximation. To emphasize the practical relevance of our proposed estimators, we illustrate their application using a real data set from head and neck cancer research.

We extend the notion of generalized Drazin-Riesz inverse introduced for bounded linear operators in Živković-Zlatanović and Cvetković (Linear Multilinear Algebra 65(6):1171–1193, 2017) to elements in a complex unital semi-simple Banach algebra. Several characterizations and properties of generalized Drazin-Riesz invertible elements are given. In particular, we extend those of Abad and Zguitti (Ann Funct Anal 12:Article number: 55, 2021), Djordjević and Stanimirovic (Czech Math J 51(3):617–634, 2001) and Živković-Zlatanović and Cvetković (2017).

In this paper, epistemic uncertainty such as the concept of fuzzy set theory has been considered for the analysis of an optimization problem. Accordingly, a fully fuzzy linear programming problem with equality fuzzy constraints has been analysed. Here the involved parameters and variables are considered in terms of trapezoidal fuzzy numbers. In this regard, a new alternative method by converting the fuzzy problem into an equivalent crisp problem has been proposed. In the methodology, for the defuzzification process linear combination-based approach for the fuzzy objective function as well as fuzzy arithmetic are used for the constraints and the non-negative restrictions. Various numerical examples have been solved and compared with the existing results for the validation.

Let ({mathbb {R}}_{alpha ,beta }(z)=z+{displaystyle sum limits _{n=2}^{infty }}frac{beta ^{n-1}Gamma (1+alpha )}{Gamma ((1+alpha )n)}z^{n}) be the normalized Rabotnov functions. The purpose of the present paper is to determine necessary and sufficient conditions and inclusion relation for the normalized Rabotnov function ({mathbb {R}}_{alpha ,beta }(z)) to be in two subclasses of analytic functions with positive coefficients. Further, we consider an integral operator related to the Rabotnov function ({mathbb {R}}_{alpha ,beta }(z)). Several examples of the main results are also considered.

In this paper, we study a memory-type porous-elastic system coupled with a neutral delay on the elasticity equation. We construct some appropriate functionals together with modified energy functional and stabilize the system exponentially depending on the wave speed, the weight of the delay, and the relaxation function.