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拓扑空间中函数上(下)极限的一些性质
引用本文:卢天秀,朱培勇,辛邦颖. 拓扑空间中函数上(下)极限的一些性质[J]. 四川轻化工学院学报, 2011, 0(3): 264-266
作者姓名:卢天秀  朱培勇  辛邦颖
作者单位:[1]四川理工学院理学院,四川自贡643000 [2]电子科技大学数学科学学院,成都611731 [3]西昌学院汽车与电子工程学院,四川西昌615013
基金项目:国家自然科学基金资助项目(10671134); 四川理工学院科研基金(2009XJKYL007)
摘    要:结合拓扑空间的特性讨论函数上(下)极限,得到了一些与实直线上几乎一致的结果。首先给出了拓扑空间中函数上(下)极限的定义。然后证明了满足第一可数性公理的拓扑空间中函数上(下)极限是子极限集的最大(小)元。针对在某点存在单调递减的可数邻域基的函数,得到了上(下)极限的等价条件和几个性质。

关 键 词:拓扑空间  上(下)极限  第一可数

Some Properities of Upper and Lower Limits of a Function on Topological Space
LU Tian-xiu,ZHU Pei-yong,XIN Bang-ying. Some Properities of Upper and Lower Limits of a Function on Topological Space[J]. Journal of Sichuan Institute of Light Industry and Chemical Technology, 2011, 0(3): 264-266
Authors:LU Tian-xiu  ZHU Pei-yong  XIN Bang-ying
Affiliation:1.School of Science,Sichuan University of Science & Engineering,Zigong 643000,China;2.School of Mathematical Science,University of Electronic Science and Technology of China,Chengdu 611731,China;3.School of Automotive and Electronic Engineering,Xichang College,Xichang 615013,China)
Abstract:Combined with properities of topological space,this paper discussed the upper and lower limits of a function,obtained some results which relatively similar to the ones on real line.First,the concept of upper and lower limits of a function in topological space is defined.Then it is proved that upper and lower limits of a function on first-countable topological space is the largest(smallest) element of sub-limit set.Also,the equivalent conditions and some properities of the function with monotone decreasing countable neighborhood basis at a point are obtained.
Keywords:topological space  upper and lower limits  first-countable
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