The closed finite-to-one mappings and their applications

  • Jie Yang
  • Shou LinEmail author


In this paper, we discuss the closed finite-to-one mapping theorems on generalized metric spaces and their applications. It is proved that point-Gδ properties, 0-snf-countability and csf-countability are invariants and inverse invariants under closed finite-to-one mappings. By the relationships between the weak first-countabilities, we obtain the closed finite-to-one mapping theorems of weak quasi-first-countability, quasi-first-countability, snf-countability, gf-countability and sof-countability. Furthermore, these results are applied to the study of symmetric products of topological spaces.


finite-to-one mappings closed mappings weak first-countability sn-networks cs-networks symmetric products 

MR Subject Classification

54B05 54B10 54C10 54D55 54D99 54E99 54G20 


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The authors would like to thank the referees for some constructive suggestions and all their efforts in order to improve this paper.


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Copyright information

© Editorial Committee of Applied Mathematics 2019

Authors and Affiliations

  1. 1.School of Mathematics and StatisticsMinnan Normal UniversityZhangzhou, FujianChina
  2. 2.Department of MathematicsNingde Normal UniversityNingde, FujianChina

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