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Scheepers猜想和Scheepers图表(彭银河)
发布时间:2023-01-11 |来源:

  Inductively approaching subsets by almost finite sets, we refute Scheepers’ conjecture under CH. More precisely, we prove the following. 

  1. Assuming CH, there is a subset of reals $X$ such that $C_p(X)$ has property ($\alpha _2$) and $X$ does not satisfy $S_1(\Gamma , \Gamma )$. 

  Applying the idea of approaching subsets by almost finite sets and using an analogous approaching, we complete the Scheepers Diagram. 

  2. $U_{fin}(\Gamma , \Gamma )$ implies $S_{fin}(\Gamma , \Omega )$. 

  3. $U_{fin}(\Gamma , \Omega )$ does not imply $S_{fin}(\Gamma , \Omega )$. More precisely, assuming CH, there is a subset of reals $X$ satisfying $U_{fin}(\Gamma , \Omega )$ such that $X$ does not satisfy $S_{fin}(\Gamma , \Omega )$. 

  These results solve three longstanding and major problems in selection principles. 

   

  Publication: 

  Transactions of The American Mathematical Society, Volume 376, Number 2, February 2023, Pages 1199–1229. 

  https://doi.org/10.1090/tran/8787 

    

  Author: 

  Yinhe Peng 

  Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing, 100190, China 

  Email: pengyinhe@amss.ac.cn 


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