Extension properties of Stone–Čech coronas and proper absolute extensors

Tom 222 / 2013

A. Chigogidze Fundamenta Mathematicae 222 (2013), 155-173 MSC: Primary 54C20, 57N20; Secondary 54D35. DOI: 10.4064/fm222-2-3


We characterize, in terms of $X$, the extensional dimension of the Stone–Čech corona $\beta X \setminus X$ of a locally compact and Lindelöf space $X$. The non-Lindelöf case is also settled in terms of extending proper maps with values in $I^{\tau }\setminus L$, where $L$ is a finite complex. Further, for a finite complex $L$, an uncountable cardinal $\tau $ and a $Z_{\tau }$-set $X$ in the Tikhonov cube $I^{\tau }$ we find a necessary and sufficient condition, in terms of $I^{\tau }\setminus X$, for $X$ to be in the class $\operatorname {AE}([L])$. We also introduce a concept of a proper absolute extensor and characterize the product $[0,1)\times I^{\tau }$ as the only locally compact and Lindelöf proper absolute extensor of weight $\tau > \omega $ which has the same pseudocharacter at each point.


  • A. ChigogidzeDepartment of Mathematics
    College of Staten Island, CUNY
    2800 Victory Blvd.
    Staten Island, NY 10314, U.S.A.

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