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Symmetric Toeplitz determinants of some classes of univalent functions 几类一元函数的对称Toeplitz行列式
IF 0.8
Afrika Matematika Pub Date : 2026-07-22 DOI: 10.1007/s13370-026-01493-z
Milutin Obradović, Nikola Tuneski
{"title":"Symmetric Toeplitz determinants of some classes of univalent functions","authors":"Milutin Obradović,&nbsp;Nikola Tuneski","doi":"10.1007/s13370-026-01493-z","DOIUrl":"10.1007/s13370-026-01493-z","url":null,"abstract":"<div><p>In this paper, we consider estimates of symmetric Toeplitz determinants <span>(T_{q,n}(f))</span> for the class <span>({mathcal {U}})</span> and for the general class <span>({mathcal {S}})</span> for certain values of <i>q</i> and <i>n</i> (<span>(q,n=1,2,3ldots )</span>).</p></div>","PeriodicalId":46107,"journal":{"name":"Afrika Matematika","volume":"37 3","pages":""},"PeriodicalIF":0.8,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148613609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Cosmological implications and causality in (f(R, L_{m}, T)) gravity theory with observational constraints 宇宙学含义和因果关系(f(R, L_{m}, T))重力理论与观测约束
IF 0.8
Afrika Matematika Pub Date : 2026-07-20 DOI: 10.1007/s13370-026-01484-0
Dinesh Chandra Maurya, Javlon Rayimbaev, Inomjon Ibragimov, Sokhibjan Muminov
{"title":"Cosmological implications and causality in (f(R, L_{m}, T)) gravity theory with observational constraints","authors":"Dinesh Chandra Maurya,&nbsp;Javlon Rayimbaev,&nbsp;Inomjon Ibragimov,&nbsp;Sokhibjan Muminov","doi":"10.1007/s13370-026-01484-0","DOIUrl":"10.1007/s13370-026-01484-0","url":null,"abstract":"<div><p>In the generalized matter-geometry coupling theory, we investigate the physical characteristics and causality of some new cosmological models for a flat, homogeneous, and isotropic spacetime filled with stiff-fluid, radiation, dust, and curvature fluid sources. We obtain a particular cosmological model corresponding to each source fluid, called Models I, II, III, and IV, respectively. We make observational constraints on each model using the joint analysis of the 31 Cosmic Chronometer (CC) Hubble dataset and 1701 Pantheon+SH0ES datasets to estimate the current values of model parameters. Using these statistical results, we have analyzed the information criteria, effective EoS parameter, causality of the models, and viability of this generalized gravity theory. Subsequently, we investigate the effective equation of state and deceleration parameter for each model. We found that all models in the late-time universe exhibit an acceleration phase, and Models II and IV show a late-time accelerating phase of the expanding universe with a transition point. We found the current values of the deceleration parameter in the range <span>(-0.9334le q_{0}le -0.5294)</span> with transition redshift <span>(0.5122le z_{t}le 0.586)</span> and the effective EoS parameter in the range <span>(-0.9556le omega _textrm{eff}le -0.6863.)</span> We analyzed the square sound speed condition <span>(c_{s}^{2}le c^{2})</span> for each model.</p></div>","PeriodicalId":46107,"journal":{"name":"Afrika Matematika","volume":"37 3","pages":""},"PeriodicalIF":0.8,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148613177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Bach almost solitons and perfect fluid spacetimes 巴赫几乎孤子和完美的流体时空
IF 0.8
Afrika Matematika Pub Date : 2026-07-20 DOI: 10.1007/s13370-026-01488-w
Krishnendu De, Arpan Sardar
{"title":"Bach almost solitons and perfect fluid spacetimes","authors":"Krishnendu De,&nbsp;Arpan Sardar","doi":"10.1007/s13370-026-01488-w","DOIUrl":"10.1007/s13370-026-01488-w","url":null,"abstract":"<div><p>In this work, we analyze the solutions to the Einstein field equations under the assumption that the gravitational field originates from a perfect fluid. Bach almost solitons on perfect fluid spacetimes are investigated with this novel and inventive method. First, we show that if a perfect fluid spacetime with concircular vector field satisfying some state equation obeys Bach almost solitons whose potential vector field is point-wise collinear with <span>(zeta )</span>, then the spacetime becomes Bach flat. Moreover, we prove that under certain restriction, if a perfect fluid spacetime with V-Ric vector field obeys steady Bach almost solitons, then the perfect fluid spacetime satisfies the state equation <span>(p=-frac{3-m}{1-m}sigma )</span> and in dimension 4, it represents phantom era under certain restriction on the associated scalars.</p></div>","PeriodicalId":46107,"journal":{"name":"Afrika Matematika","volume":"37 3","pages":""},"PeriodicalIF":0.8,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148613176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Vertex degree in maximal strong product of fuzzy graphs 模糊图的极大强积中的顶点度
IF 0.8
Afrika Matematika Pub Date : 2026-07-20 DOI: 10.1007/s13370-026-01491-1
Talal Ali Al-Hawary
{"title":"Vertex degree in maximal strong product of fuzzy graphs","authors":"Talal Ali Al-Hawary","doi":"10.1007/s13370-026-01491-1","DOIUrl":"10.1007/s13370-026-01491-1","url":null,"abstract":"<div><p>This work introduces the maximal strong product of fuzzy graphs as a modification of the strong product previously introduced by Al-Hawary [2]. The paper establishes new connectedness criteria and develops vertex-degree properties for this product, including sufficient conditions under which the maximal strong product of regular fuzzy graphs remains regular.</p></div>","PeriodicalId":46107,"journal":{"name":"Afrika Matematika","volume":"37 3","pages":""},"PeriodicalIF":0.8,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148613259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
On the relative commutativity degree of subalgebra of a finite-dimensional Lie algebra 有限维李代数的子代数的相对交换度
IF 0.8
Afrika Matematika Pub Date : 2026-07-20 DOI: 10.1007/s13370-026-01489-9
Akram Chareh Khah Moghaddam, Ahmad Erfanian, Afsaneh Shamsaki
{"title":"On the relative commutativity degree of subalgebra of a finite-dimensional Lie algebra","authors":"Akram Chareh Khah Moghaddam,&nbsp;Ahmad Erfanian,&nbsp;Afsaneh Shamsaki","doi":"10.1007/s13370-026-01489-9","DOIUrl":"10.1007/s13370-026-01489-9","url":null,"abstract":"<div><p>This paper introduces and studies the <i>relative commutativity degree</i> of a subalgebra <span>(H)</span> for a finite-dimensional Lie algebra <span>(L)</span> over a finite field <span>(mathbb {F}_q)</span>, denoted by <span>(d(H, L))</span>. This notion generalizes the known commutativity degree <span>(d(L))</span> of a Lie algebra. We establish several foundational properties, bounds, and structural theorems for <span>(d(H, L))</span>. In particular, we provide upper bounds depending on whether <span>(H)</span> is abelian or non-abelian and characterize the subalgebras that attain these upper bounds for <span>(d(H, L))</span>.</p></div>","PeriodicalId":46107,"journal":{"name":"Afrika Matematika","volume":"37 3","pages":""},"PeriodicalIF":0.8,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148613175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Refined Hermite–Hadamard inequalities with applications in probability 改进Hermite-Hadamard不等式在概率中的应用
IF 0.8
Afrika Matematika Pub Date : 2026-07-20 DOI: 10.1007/s13370-026-01483-1
Yamin Sayyari, Hasan Barsam, Slavica Ivelić Bradanović
{"title":"Refined Hermite–Hadamard inequalities with applications in probability","authors":"Yamin Sayyari,&nbsp;Hasan Barsam,&nbsp;Slavica Ivelić Bradanović","doi":"10.1007/s13370-026-01483-1","DOIUrl":"10.1007/s13370-026-01483-1","url":null,"abstract":"<div><p>This paper establishes several novel Hermite–Hadamard type inequalities for convex functions on closed intervals. In contrast to classical results, the proposed inequalities incorporate logarithmic weights together with variable subinterval boundaries <span>(a&lt;a_{1}le b_{1}&lt;b)</span> providing a more flexible method for integral estimation. Furthermore, we develop a probabilistic interpretation by viewing a convex function as a probability density function, which enables the derivation of new bounds for event probabilities. In particular, we obtain estimates of the form </p><div><div><span>$$ mathbb {P}left( left| X-frac{3a+b}{4}right| le frac{b-a}{8}right) +mathbb {P}left( left| X-frac{a+3b}{4}right| le frac{b-a}{8}right) le frac{b-a}{16}left( f(a)+f(b)right) +frac{3}{8}. $$</span></div></div><p>A numerical example is included to demonstrate the improvement over the classical Hermite–Hadamard inequality. Finally, we propose several conjectures related to probability concentration for convex distributions, highlighting potential directions for future research.</p></div>","PeriodicalId":46107,"journal":{"name":"Afrika Matematika","volume":"37 3","pages":""},"PeriodicalIF":0.8,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148613234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Hyperstability of a quartic functional equation in complete quasi-2-normed space 完全拟2赋范空间中四次泛函方程的超稳定性
IF 0.8
Afrika Matematika Pub Date : 2026-07-18 DOI: 10.1007/s13370-026-01485-z
Ravinder Kumar Sharma, Meenu Prajapati, Aasish Kumar Rawat, Sumit Chandok
{"title":"Hyperstability of a quartic functional equation in complete quasi-2-normed space","authors":"Ravinder Kumar Sharma,&nbsp;Meenu Prajapati,&nbsp;Aasish Kumar Rawat,&nbsp;Sumit Chandok","doi":"10.1007/s13370-026-01485-z","DOIUrl":"10.1007/s13370-026-01485-z","url":null,"abstract":"<div><p>In this paper, we study the quartic functional equation </p><div><div><span>$$ g(kvarpi +varkappa )+g(kvarpi -varkappa ) =k^2bigl [g(varpi +varkappa )+g(varpi -varkappa )bigr ] +2k^2(k^2-1)g(varpi )-2(k^2-1)g(varkappa ), $$</span></div></div><p>for a fixed integer <span>(kge 2.)</span> The general solution of the functional equation is established, and its stability and hyperstability are proved using the fixed point method in the framework of complete quasi-2-normed spaces. Furthermore, several corollaries are established as applications of the main theorems, through which various existing results on quartic functional equations are generalized, and extended, thereby enriching the stability theory of quartic functional equations in complete quasi-2-normed spaces.</p></div>","PeriodicalId":46107,"journal":{"name":"Afrika Matematika","volume":"37 3","pages":""},"PeriodicalIF":0.8,"publicationDate":"2026-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148466505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Fiducial inference on lifetime performance index based on type-II censored samples 基于ii型截尾样本的寿命性能指标的基准推断
IF 0.8
Afrika Matematika Pub Date : 2026-07-17 DOI: 10.1007/s13370-026-01487-x
Kuntal Bera, M. Z. Anis
{"title":"Fiducial inference on lifetime performance index based on type-II censored samples","authors":"Kuntal Bera,&nbsp;M. Z. Anis","doi":"10.1007/s13370-026-01487-x","DOIUrl":"10.1007/s13370-026-01487-x","url":null,"abstract":"<div><p>The lifetime performance index <span>(C_{L})</span> measures the performance of a process in terms of the lifetime of produced items. In this article, we use the fiducial approach to estimate the lower confidence bound of the lifetime performance index under some location-scale distributions. We consider three important lifetime distributions: two-parameter exponential, two-parameter Rayleigh and Weibull distribution. Often lifetime data comes as censored data instead of complete data. Here we consider type-II censored samples. The fiducial quantities are estimated based on the MLE. The performance of our proposed lower confidence bound using fiducial approach is compared with some existing lower confidence bound in terms of their coverage probability and average value. It is observed through the discussion that the overall performance of our proposed lower confidence bound is better than the existing lower confidence bounds. Hence the proposed method estimates a very reliable confidence bound. An example is given to illustrate the applicability of our proposed lower confidence bound in industry.</p></div>","PeriodicalId":46107,"journal":{"name":"Afrika Matematika","volume":"37 3","pages":""},"PeriodicalIF":0.8,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148466332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Solving variational inequalities over solutions of split equality common fixed point problems for demicontractive mappings 求解半收缩映射的分裂相等公共不动点问题解上的变分不等式
IF 0.8
Afrika Matematika Pub Date : 2026-07-17 DOI: 10.1007/s13370-026-01486-y
Khairul Saleh
{"title":"Solving variational inequalities over solutions of split equality common fixed point problems for demicontractive mappings","authors":"Khairul Saleh","doi":"10.1007/s13370-026-01486-y","DOIUrl":"10.1007/s13370-026-01486-y","url":null,"abstract":"<div><p>In this manuscript, we propose two average viscosity iterative schemes to approximate solutions of split equality common fixed point problems, which also address a pair of variational inequality problems governed by a broad class of demi-contractive mappings. We present examples of <span>(beta )</span>-demicontractive mappings that are neither nonexpansive nor quasi-nonexpansive, and not strictly pseudo-contractive. The strong convergence of these methods is established in Hilbert spaces, extending and generalizing earlier studies. Numerical experiments implemented in Python are provided to illustrate the convergence of our results.</p></div>","PeriodicalId":46107,"journal":{"name":"Afrika Matematika","volume":"37 3","pages":""},"PeriodicalIF":0.8,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148466331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Fuzzy harmonic mean-based method for solving intuitionistic fuzzy multi-objective linear fractional optimization problems and its application in organizational planning 基于模糊调和均值的直觉模糊多目标线性分式优化问题求解方法及其在组织规划中的应用
IF 0.8
Afrika Matematika Pub Date : 2026-07-16 DOI: 10.1007/s13370-026-01473-3
Vaishaly Verma, Pitam Singh
{"title":"Fuzzy harmonic mean-based method for solving intuitionistic fuzzy multi-objective linear fractional optimization problems and its application in organizational planning","authors":"Vaishaly Verma,&nbsp;Pitam Singh","doi":"10.1007/s13370-026-01473-3","DOIUrl":"10.1007/s13370-026-01473-3","url":null,"abstract":"<div><p>Fractional programming provides a robust and efficient mathematical framework for dealing with real-world optimization problems where objectives are expressed as ratio form. When such systems are affected by uncertainty and imprecision, intuitionistic fuzzy fractional programming becomes an effective tool for capturing both membership and non-membership uncertainties in decision variables and parameters. This study introduces a novel algorithm to address fuzzy multi-objective linear fractional programming problems in which the uncertainty present in the objective functions and constraint parameters is handled by the triangular intuitionistic fuzzy numbers. The primary aim is to develop a simple yet efficient solution methodology for multi-objective linear fractional programming problems under intuitionistic fuzzy environments. The proposed algorithm starts by using a component-wise method to transform fuzzy objective functions into equivalent crisp forms. To handle the fuzzy constraints, an appropriate ranking function is utilized, converting them into deterministic form. The fractional components are then linearized using a suitable variable transformation, yielding a crisp multi-objective linear programming problem. This multi-objective linear programming problem is further transformed into a single-objective linear programming problem using the fuzzy harmonic mean approach, and then a fuzzy goal programming technique is subsequently applied to obtain the optimal solution. Finally, a ranking formula is used to defuzzify the fuzzy results into crisp outputs. The effectiveness and practicality of the proposed method are illustrated through the solution of one existing numerical example and one real-world case, with comparisons highlighting the superiority of the proposed approach over existing techniques.</p></div>","PeriodicalId":46107,"journal":{"name":"Afrika Matematika","volume":"37 3","pages":""},"PeriodicalIF":0.8,"publicationDate":"2026-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148466074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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