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FIXED POINT THEOREMS AND BEST APPROXIMATION IN CONVEX METRIC SPACES 被引量:2
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作者 I.Beg N.Shahzad M.Iqbal 《Analysis in Theory and Applications》 1992年第4期97-105,共9页
Results regarding best approximation and best Simultaneous approximation on convex metric spaces are Obtained.Existence of fixed points for an ultimately nonexpansive semigroup of mappings is also shown.
关键词 CIG FIXED point THEOREMS AND best APPROXIMATION IN CONVEX METRIC SPACES
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BEST PROXIMITY POINT THEOREMS FOR SINGLE- AND SET-VALUED NON-SELF MAPPINGS
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作者 Moosa GABELEH 《Acta Mathematica Scientia》 SCIE CSCD 2014年第5期1661-1669,共9页
We study the existence of best proximity points for single-valued non-self map-pings. Also, we prove a best proximity point theorem for set-valued non-self mappings in metric spaces with an appropriate geometric prope... We study the existence of best proximity points for single-valued non-self map-pings. Also, we prove a best proximity point theorem for set-valued non-self mappings in metric spaces with an appropriate geometric property. Examples are given to support the usability of our results. 展开更多
关键词 best proximity point fixed point P-property
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COMMON FIXED POINTS WITH APPLICATIONS TO BEST SIMULTANEOUS APPROXIMATIONS
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作者 Sumit Chandok T. D. Narang 《Analysis in Theory and Applications》 2012年第1期1-12,共12页
For a subset K of a metric space (X,d) and x ∈ X,Px(x)={y ∈ K : d(x,y) = d(x,K)≡ inf{d(x,k) : k ∈ K}}is called the set of best K-approximant to x. An element go E K is said to be a best simulta- neous ... For a subset K of a metric space (X,d) and x ∈ X,Px(x)={y ∈ K : d(x,y) = d(x,K)≡ inf{d(x,k) : k ∈ K}}is called the set of best K-approximant to x. An element go E K is said to be a best simulta- neous approximation of the pair y1,y2 E ∈ if max{d(y1,go),d(y2,go)}=inf g∈K max {d(y1,g),d(y2,g)}.In this paper, some results on the existence of common fixed points for Banach operator pairs in the framework of convex metric spaces have been proved. For self mappings T and S on K, results are proved on both T- and S- invariant points for a set of best simultaneous approximation. Some results on best K-approximant are also deduced. The results proved generalize and extend some results of I. Beg and M. Abbas^[1], S. Chandok and T.D. Narang^[2], T.D. Narang and S. Chandok^[11], S.A. Sahab, M.S. Khan and S. Sessa^[14], P. Vijayaraju^[20] and P. Vijayaraju and M. Marudai^[21]. 展开更多
关键词 Banach operator pair best approximation demicompact fixed point STAR-SHAPED NONEXPANSIVE asymptotically nonexpansive and uniformly asymptot-ically regular maps
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Determination of a Cut-Off Point of a Scale for Achievement Motive in Geriatrics That Predicts the Frequency of Undertaking Instrumental Activities of Daily Living in Community-Dwelling Elderly People
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作者 Nobuyuki Sano Hisato Nakazono 《Advances in Aging Research》 2019年第6期107-118,共12页
Background: Among elderly people, rehabilitation is important for reducing the risk of falls and hospitalization and to maintain an independent life for longer. Motivation is a factor for elderly people to lead an act... Background: Among elderly people, rehabilitation is important for reducing the risk of falls and hospitalization and to maintain an independent life for longer. Motivation is a factor for elderly people to lead an active daily life and leave home more frequently. Purpose: The purposes of this study were to determine the optimal cut-off point in the Scale for Achievement Motive in Geriatrics (SAMG) that could identify individuals as inactive or active, based on the Frenchay Activities Index (FAI), and to compare characteristics between active and inactive groups classified by the cut-off point. Methods: A cross-sectional study of 285 community-dwelling elderly people measured SAMG and FAI and physical function. Receiver operating characteristic (ROC) analysis was used to calculate the area under the curve (AUC) that was the optimal cut-off point for the SAMG total score, with the associated sensitivity and 1-specificity when compared with the FAI results. Demographic parameters and physical function were compared between two groups defined by cut-off point. Results: The AUC was 0.78, the optimal cut-off for SAMG total score for indicating inactivity was ≤48, the sensitivity was 77.98% and the 1-specificity was 75.00%. The group with SAMG score >48 was characterized by a significantly higher proportion of women, fewer people sharing a house, and participation in more hobbies. Discussion: A cut-off point of 48 in the SAMG could be a predictive index of motivation toward goals for individuals with inactive daily activities. The group with score higher than the cut-off was characterized by more women, fewer people living together, and more hobbies than the group with lower scores. 展开更多
关键词 ACHIEVEMENT MOTIVE INSTRUMENTAL Activities of Daily Living cut-off point Preventive Care COMMUNITY-DWELLING Elderly People
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Mount Huang: Seeking for Best Balance Point between Protectionand Development
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《China's Foreign Trade》 2002年第9期25-28,共4页
关键词 World UNESCO Seeking for best Balance point between Protectionand Development Mount Huang
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AN APPLICATION OF A FIXED POINT THEOREM TO BEST SIMULTANEOUS APPROXIMATION
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作者 Isinat Beg Naseer Shahzad 《Analysis in Theory and Applications》 1994年第3期1-4,共4页
Using a recent result regarding the fixed points of multivalued mappings, the existence of invariant best simultaneous approximation in chainable metric space is proved.
关键词 AN APPLICATION OF A FIXED point THEOREM TO best SIMULTANEOUS APPROXIMATION
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偏序集上非自映射的最佳逼近点定理
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作者 陈丽君 《长春师范大学学报》 2024年第6期1-4,共4页
给出广义收缩非自映射的概念,证明了该非自映射在偏序集上的最佳逼近点定理,并举例支持本文的研究结果.所得结果推广了相关文献的结论,尤其无偏序关系的距离空间中非自映射的最佳逼近点定理是本文结论的一个特殊情况.
关键词 最佳逼近点 广义压缩 收敛性 偏序集
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应用混合线性模型对白桦家系速生性及稳定性分析与选择 被引量:1
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作者 周文戈 孙越 +7 位作者 张杰 文浩雨 李慧玉 高彩球 王超 张庆祝 姜静 刘桂丰 《东北林业大学学报》 CAS CSCD 北大核心 2024年第9期1-7,共7页
为了选出白桦半同胞家系中速生且稳定的优异家系用于种子园改建,以永吉、尚志和庆安试验点的8年生白桦半同胞家系试验林为研究对象,调查其生长性状和适应性。采用误差异质混合线性模型,对各性状进行了多地点固定效应和随机效应分析,通... 为了选出白桦半同胞家系中速生且稳定的优异家系用于种子园改建,以永吉、尚志和庆安试验点的8年生白桦半同胞家系试验林为研究对象,调查其生长性状和适应性。采用误差异质混合线性模型,对各性状进行了多地点固定效应和随机效应分析,通过最佳线性无偏预测(BLUP)法估算各家系的材积育种值,并结合基因型主效应与基因型-环境互作效应(GGE)双标图,联合分析各家系的速生性和稳定性。结果表明:(1)白桦半同胞家系胸径、单株材积和保存率等性状的地点效应显著(P<0.01);除保存率外,各性状在家系×地点的互作效应均达到显著水平(Z值>1.5)。各试验点的方差分析结果表明,除尚志和庆安试验点保存率外,其余性状在家系间的差异均达到极显著水平(P<0.01)。尚志、永吉和庆安试验点各性状中,变异系数最大的均为单株材积,分别为40.74%、47.62%和41.67%。(2)将综合育种值从大到小排序,若按照前10%的入选率确定各试验点优良家系,则在永吉、尚志和庆安各选出了相应的7个家系,其单株材积的平均遗传增益分别为6.20%、9.44%和8.79%。(3)GGE双标图分析结果表明,3个试验点被分为3个适生区;各家系在不同试验点中的表现不同,在庆安、永吉和尚志试验点表现最好的分别为1-43、1-42和1-39家系,结合生长量及稳定性的数据排名,综合性状表现最好的是3-29、3-13、3-38、3-16、3-14、3-42和3-17等7个家系,平均单株材积遗传增益为10.41%。白桦子代生长性状受基因型、基因型与环境互作影响显著。依据BLUP数据的GGE双标图分析结果,综合3试验点的速生及稳定性,选出7个优良家系。 展开更多
关键词 白桦 多点试验 最佳线性无偏预测(BLUP) 基因型主效加基因型-环境互作效应(GGE)双标图 基因型与环境互作
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多级串并联离心泵运行特性研究 被引量:1
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作者 王红超 魏志聪 +1 位作者 李晓俊 朱祖超 《流体机械》 CSCD 北大核心 2024年第2期54-59,91,共7页
为了研究泵系统串并联的工作特性,设计了一种由3台泵组成的双进口、双出口的串并联组合形式,通过试验和数值模拟结合的手段对每台泵能量特性进行分析。结果表明,通过对工作模式3不同流量下各泵的流量进行监测,发现并联的一级泵之间流量... 为了研究泵系统串并联的工作特性,设计了一种由3台泵组成的双进口、双出口的串并联组合形式,通过试验和数值模拟结合的手段对每台泵能量特性进行分析。结果表明,通过对工作模式3不同流量下各泵的流量进行监测,发现并联的一级泵之间流量分布规律并不相同,最大流量差为0.15 Q_(d),两者之间流量差值随流量的不断增大呈现先增大后减小的规律;出口1的扬程与M2的扬程较为接近,最大差值为0.188 H_(d),与M1的扬程差值较大,最大差值为1.139 H_(d);出口2的扬程基本不随工况发生变化,但是受上游2台并联一级泵的混合流态影响会产生波动。研究结果可为离心泵复杂串并联系统的设计和改进提供参考。 展开更多
关键词 离心泵 串并联 能量特性 流量分配 高效点
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黄土地质灾害评价因子地形起伏度提取最佳尺度研究:以榆林市米脂县为例
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作者 孟晓捷 郭小鹏 +2 位作者 薛强 冯卫 洪勃 《西北地质》 CAS CSCD 北大核心 2024年第6期234-243,共10页
目前地质灾害相关评价工作中,部分研究人员对于“地形起伏度”(也称相对坡高)选取最佳窗口单元进行提取存在着一定程度的随意性和主观性,致使取得的地形起伏度参数与研究区实际情况相比存在一定的误差。后续地灾评价中,无论采用以栅格... 目前地质灾害相关评价工作中,部分研究人员对于“地形起伏度”(也称相对坡高)选取最佳窗口单元进行提取存在着一定程度的随意性和主观性,致使取得的地形起伏度参数与研究区实际情况相比存在一定的误差。后续地灾评价中,无论采用以栅格为基础的信息量模型还是现今普遍流行的各类机器学习方法,其评价因子本身的误差甚至错误会导致评价结果可靠性降低。笔者基于Arc GIS平台,利用陕西省榆林市米脂县分辨率为2 m的DEM数据,采用均值变点分析法,通过两轮分析,数量分别为10×10和1×1的矩形窗口逐渐逼近研究区地形起伏度的最佳统计单元,计算出该县地形起伏度为0~256.60 m,最佳统计单元为59×59的窗格,栅格单元边长为2 m,提取窗格边长为118 m,对应提取面积为13924 m^(2)。随后依据陕北黄土地区历史滑坡及崩塌的易发坡高统计将米脂县地形起伏度等分为<20 m、20~40 m、40~60 m、60~80 m、>80 m等5个区间,受原始地形条件及削坡建房、建厂等综合影响,40~80 m为灾害隐患发育的主要区间,灾害隐患点占比为88.60%。结合米脂县地质灾害隐患点信息量值和灾害点密度对比曲线,结果显示二者有很好的相关性,体现了地形起伏度统计单元选取和区间划分的合理性。本研究所采用的高精度DEM数据的计算及分析结果,首先避免了目视寻找拐点的弊端,其次在黄土高原地区千沟万壑的地貌条件中能够满足数字地形分析与精细化地质灾害调查的需求,可为黄土高原区地质灾害评价防治及黄河中上游流域的水土流失治理与生态环境保护提供一定的技术支撑。 展开更多
关键词 黄土地质灾害 地形起伏度 均值变点法 最佳窗口单元 米脂县
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基于最佳线性无偏预测的精密单点定位方法
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作者 陈寅秋 李英冰 曾文宪 《地理空间信息》 2024年第6期15-19,共5页
卫星导航定位中,卡尔曼滤波是快速处理海量观测数据,精确解算位置坐标的常用方法。为解决实际定位解算时需要计算部分参数的近似值作为先验信息的问题,引入最佳线性无偏预测理论对无先验信息的参数初值进行估计并使用其残差方差代替未... 卫星导航定位中,卡尔曼滤波是快速处理海量观测数据,精确解算位置坐标的常用方法。为解决实际定位解算时需要计算部分参数的近似值作为先验信息的问题,引入最佳线性无偏预测理论对无先验信息的参数初值进行估计并使用其残差方差代替未知的先验方差参与计算。在静态和动态情形下进行了非差非组合精密单点定位实验并与传统滤波方法进行对比。算例结果表明,基于最佳线性无偏预测的精密单点定位算法可以对无先验信息的参数估计初值和方差信息,且定位精度与卡尔曼滤波一致。 展开更多
关键词 最佳线性无偏预测 卡尔曼滤波 精密单点定位
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考虑环境成本综合效益的泾河流域最佳管理措施评价与筛选
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作者 阮炳南 吴磊 +1 位作者 郭嘉薇 杜佰林 《中国环境科学》 EI CAS CSCD 北大核心 2024年第1期319-328,共10页
基于土壤和水评估工具(SWAT)评估9种单一最佳管理措施(BMPs)及其不同组合共计103种BMPs情景布设对非点源污染的消减效率,并基于信息熵的多属性决策方法评估泾河流域BMPs实施成本和非点源控制有效性之间的权衡.研究发现,SWAT模型在泾河... 基于土壤和水评估工具(SWAT)评估9种单一最佳管理措施(BMPs)及其不同组合共计103种BMPs情景布设对非点源污染的消减效率,并基于信息熵的多属性决策方法评估泾河流域BMPs实施成本和非点源控制有效性之间的权衡.研究发现,SWAT模型在泾河流域非点源污染模拟中适用性较好,不同的BMPs对非点源污染负荷削减量存在较大差异,组合BMPs比单一BMPs在降低非点源污染负荷方面表现更好.在农业耕作过程中减少化肥50%的施用量、将坡度大于25°的农田退耕还草以及在河道进行植草水道措施建设是泾河流域具有最大环境成本综合效益值的优选组合BMPs. 展开更多
关键词 非点源 最佳管理措施 环境成本综合效益 泾河流域
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切割叶轮尺寸对单叶片离心泵性能影响
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作者 周龙德 白万本 《广州化工》 CAS 2024年第14期112-115,共4页
采用实验和CFD模拟计算两种方法对3种尺寸单叶片泵叶轮进行了研究,讨论了单叶片泵的直径变化对其性能参数的影响。实验在水力机械实验室进行,通过CFD计算验证了实验结果,通过CFD对最佳效率点(BEP)附近的水力参数进行模拟计算,结果表明,... 采用实验和CFD模拟计算两种方法对3种尺寸单叶片泵叶轮进行了研究,讨论了单叶片泵的直径变化对其性能参数的影响。实验在水力机械实验室进行,通过CFD计算验证了实验结果,通过CFD对最佳效率点(BEP)附近的水力参数进行模拟计算,结果表明,当叶轮直径变化达到88.6%时,最佳效率点(BEP)的变化规律是明显的。为预测单叶片离心泵最佳工况点的变化和创建型谱图提供了重要理论依据。 展开更多
关键词 切割叶轮 单叶片离心泵 不对称叶轮 平衡 最佳效率点
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Sedimentation retention basin utilization for best management practice 被引量:2
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作者 Zaheer Iqbal 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2003年第5期662-668,共7页
Approaches to the artificial impoundment and theoretical design of sedimentation retention basin are reviewed with particular attention to best management practice(BMP) to control agriculture and surface runoff. Sedim... Approaches to the artificial impoundment and theoretical design of sedimentation retention basin are reviewed with particular attention to best management practice(BMP) to control agriculture and surface runoff. Sediments retention basins are the small version of farm pond used where a criteria of farm pond is not met. Such basin traps the pollutants and suspended solids prior to entry into streams and lakes. The study is focused with special reference to the assessment and control of non point source pollution(NPSP) from the sub basin area of Tai Lake in the Xishan County of Wuxi City of China. The author suggested two different approaches to conduct this study including theoretical design for sedimentation retention basin and computation of flow, sediment transport and deposition during the artificial impoundment of retention basin for BMP's utilization. Theoretical design will provide a useful function as a first line defense against the movement of sediments and transport of pollutants into the Tai Lake while the assessment of sediments deposition will help to make its proper use and periodic cleanup. 展开更多
关键词 agriculture runoff artificial impoundment best management practice sediment retention basin Tai Lake sub basin non point source pollution
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Is the present cut-point to define type 2 diabetes appropriate in Latin-Americans? 被引量:1
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作者 Patricio López-Jaramillo Carlos Velandia-Carrillo +1 位作者 Diego Gómez-Arbeláez Martin Aldana-Campos 《World Journal of Diabetes》 SCIE CAS 2014年第6期747-755,共9页
The diagnosis of diabetes mellitus type 2(DM2) is based either on increased plasma glucose or Glycated hemoglobin levels. Since these measures are the only means for diagnosis of DM2, they must be well adapted to each... The diagnosis of diabetes mellitus type 2(DM2) is based either on increased plasma glucose or Glycated hemoglobin levels. Since these measures are the only means for diagnosis of DM2, they must be well adapted to each population according to their metabolic characteristics, given that these may vary in each population. The World Health Organization(WHO) determined the cut-points of plasma glucose levels for the diagnosis of DM2 by associating hyperglycemia with the risk of a specific microvascular complication-retinopathy. Cardiovascular diseases are however the principal causes of mortality in patients with DM2 and we reported that in the Colombo-Ecuadorian population impaired fasting glucose and impaired glucose tolerance are both riskmarkers for myocardial infarction. We propose that the current cut-points accepted by the WHO need to be revaluated in populations such as Latin America and that there should be lower cut points for glycaemia in this population, to reduce the prevalence of cardiovascular complications associated with DM2. 展开更多
关键词 Type 2 diabetes cut-off points Cardiovascular diseases Plasma glucose Coronary disease
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A KY FAN MATCHING THEOREM FOR TRANSFER COMPACTLY OPEN COVERS AND THE APPLICATION TO THE FIXED POINT 被引量:18
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作者 文开庭 《数学物理学报(A辑)》 CSCD 北大核心 2006年第B12期1159-1165,共7页
In this article, a Ky Fan matching theorem for transfer compactly open covers is established. As applications, a Fan-Browder coincidence theorem, a Ky Fan best approximation theorem and a Brouwer-Schauder-Rothe type f... In this article, a Ky Fan matching theorem for transfer compactly open covers is established. As applications, a Fan-Browder coincidence theorem, a Ky Fan best approximation theorem and a Brouwer-Schauder-Rothe type fixed point theorem are obtained. 展开更多
关键词 超凸度量空间 最优逼近 固定点 匹配定理
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BEST APPROXIMATION THEOREM FOR SET-VALUED MAPPINGSWITHOUT CONVEX VELUES AND CONTINUITY
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作者 丁协平 2何诣然 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1998年第9期831-836,共6页
In this paper, a new concept of weakly ,convex graph for set-valued mappings is introduced and studied. By using the concept , some new coincidence, the bestapproximation and fixed point-theorems are obta... In this paper, a new concept of weakly ,convex graph for set-valued mappings is introduced and studied. By using the concept , some new coincidence, the bestapproximation and fixed point-theorems are obtained. 展开更多
关键词 best approximation COINCIDENCE fixed point topological vectorspace
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A Class of Iteration Method for the Best Approximation Problems
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作者 Wang Deren Zhao Fengguang (College of Sciences) 《Advances in Manufacturing》 SCIE CAS 1998年第1期18-24,共7页
We propose a class of iteration methods searching the best approximately generalized polynomial, which has parallel computational function and converges to the exact solution quadratically. We first transform it into ... We propose a class of iteration methods searching the best approximately generalized polynomial, which has parallel computational function and converges to the exact solution quadratically. We first transform it into a special system of nonlinear equations with constraint, then by using to certain iteration method, we combine the two basic processes of the Remes method into a whole such that the iterative process of the system of nonlinear equations and the computation of the solution to the system of linear equations proceed alternately. A lot of numerical examples show that this method not only has good convergence property but also always converges to the exact solution of the problem accurately and rapidly for almost all initial approximations . 展开更多
关键词 best approximation Chebyshev alternating point set Remes method
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SOME GENERALIZATIONS OF KY FAN'S BEST APPROXIMATION THEOREM
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作者 A.R.Khan N.Hussain A.B.Thaheem 《Analysis in Theory and Applications》 2004年第2期189-198,共10页
We pressent new Ky Fan type best approximation theorems for a discontinuous multivalued map on metrizable topological vector spaces and hyperconvex spaces. In addition, fixed point results are derived for the map stud... We pressent new Ky Fan type best approximation theorems for a discontinuous multivalued map on metrizable topological vector spaces and hyperconvex spaces. In addition, fixed point results are derived for the map studied. Our work generalizes severl results in approximation theory. 展开更多
关键词 best approximation fixed point * -nonexpansive multivalued map almost quasi-convex function metrizable topological vector space hyperconvex space
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Menger PM空间中约束不等式条件下的最优化问题
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作者 吴照奇 朱传喜 袁成桂 《应用数学》 北大核心 2023年第2期487-496,共10页
本文通过研究一类最佳逼近点的问题,讨论了T-完备Menger PM空间上关于两个偏序的不等式约束的一类最优化问题解的存在性,所得结果推广了许多文献中的相关结果.此外,给出一个例子来阐明主要结果的有效性.
关键词 Menger PM空间 偏序 约束不等式 最佳逼近点 最优化
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